Shock wave boundary layer interaction studied by high-speed schlieren

Shock wave boundary layer interactions at compression ramps have been examined by high-speed schlieren. A total of six ramps with angles ranging from 20 deg to 30 deg, the ramp angle effect on the SWBLI is thus studied. The present high-speed schlieren with a frame rate of 20 kHz generates a large ensemble of 9000 images, which secures the convergence of the statistics of the schlieren intensity. The rms of the schlieren intensity is of great interest, as it enables visualisation of the flow features that are not observable in the raw schlieren images, such as the corner separation/low momentum region, the spot of strong flow unsteadiness right after the shock wave and the location of the peak fluctuation over the ramp. Through the present systematic experimental investigation of SWBLI, the highspeed schlieren is demonstrated to be of great capability for SWBLI study

Coexistence of superconductivity and antiferromagnetism in self-doped bilayer t-t'-J model

A self-doped bilayer t-t'-J model of an electron- and a hole-doped planes is studied by the slave-boson mean-field theory. A hopping integral between the differently doped planes, which are generated by a site potential, are renormalized by the electron-electron correlation. We find coexistent phases of antiferromagnetic (AFM) and superconducting orders, although the magnitudes of order parameters become more dissimilar in the bilayer away from half-filling. Fermi surfaces (FS's) with the AFM order show two pockets around the nodal and the anti-nodal regions. These results look like a composite of electron- and hole-doped FS's. In the nodal direction, the FS splitting is absent even in the bilayer system, since one band is flat due to the AFM order.Comment: 6 pages, 4 figure

Morphological evolution of a 3D CME cloud reconstructed from three viewpoints

The propagation properties of coronal mass ejections (CMEs) are crucial to predict its geomagnetic effect. A newly developed three dimensional (3D) mask fitting reconstruction method using coronagraph images from three viewpoints has been described and applied to the CME ejected on August 7, 2010. The CME's 3D localisation, real shape and morphological evolution are presented. Due to its interaction with the ambient solar wind, the morphology of this CME changed significantly in the early phase of evolution. Two hours after its initiation, it was expanding almost self-similarly. CME's 3D localisation is quite helpful to link remote sensing observations to in situ measurements. The investigated CME was propagating to Venus with its flank just touching STEREO B. Its corresponding ICME in the interplanetary space shows a possible signature of a magnetic cloud with a preceding shock in VEX observations, while from STEREO B only a shock is observed. We have calculated three principle axes for the reconstructed 3D CME cloud. The orientation of the major axis is in general consistent with the orientation of a filament (polarity inversion line) observed by SDO/AIA and SDO/HMI. The flux rope axis derived by the MVA analysis from VEX indicates a radial-directed axis orientation. It might be that locally only the leg of the flux rope passed through VEX. The height and speed profiles from the Sun to Venus are obtained. We find that the CME speed possibly had been adjusted to the speed of the ambient solar wind flow after leaving COR2 field of view and before arriving Venus. A southward deflection of the CME from the source region is found from the trajectory of the CME geometric center. We attribute it to the influence of the coronal hole where the fast solar wind emanated from.Comment: ApJ, accepte

Interlayer couplings and the coexistence of antiferromagnetic and d-wave pairing order in multilayer cuprates

A more extended low density region of coexisting uniform antiferromagnetism and d-wave superconductivity has been reported in multilayer cuprates, when compared to single or bilayer cuprates. This coexistence could be due to the enhanced screening of random potential modulations in inner layers or to the interlayer Heisenberg and Josephson couplings. A theoretical analysis using a renormalized mean field theory, favors the former explanation. The potential for an improved determination of the antiferromagnetic and superconducting order parameters in an ideal single layer from zero field NMR and infrared Josephson plasma resonances in multilayer cuprates is discussed.Comment: 6 pages, 2 figure

Fungicides application timing, sequencing, and tank mixing for controlling blight in chickpea

Non-Peer ReviewedTotal crop losses can result from ascochyta blight on chickpea (caused by Ascochyta rabiei). A study was conducted to investigate effective fungicide application strategies in particular fungicide application timing as well as product choices, sequencing and mixtures for blight control. In addition, this study is expected to provide information on resistance management through fungicide rotations, mixtures or sequences. Fungicide trials were conducted in Saskatoon and Swift Current using Bravo 500, Quadris, Headline, BAS510 and Dithane in various sequences or tank mixes on cultivars Myles and CDC Yuma. Only Bravo 500 is registered on chickpea. Quadris had emergency registration in 2002. Applications were timed at the seedling stage, pre-flower, early-flower, late-flower and the podding stages. These results relate to the trial at Swift Current. Cultivar CDC Yuma developed higher infection levels than Myles. The level of disease control by each fungicide treatment was dependent on cultivar. The above average rainfall in Swift Current increased the level of blight severity and consequently it required several sprays especially on cultivar CDC Yuma to protect the crop. Cool wet weather towards the end of the season also delayed maturity and affected yield and seed quality. Disease severity was 97% and 82% in the untreated plots of CDC Yuma and Myles, respectively. In treated plots, it ranged from 13-50% in Myles and 15-96% in CDC Yuma. The yields varied from 434 to1956 kg/ha for CDC Yuma and 1430 to 2627 kg/ha for Myles. When spraying started before symptoms (per calender sprays with five applications), the high rate of Dithane at 2.44 kg a.i./ha reduced disease severity and increased yield more than the low rate of Dithane at 1.68kg a.i./ha. Sequencing Headline and Dithane in the per calender spray was better than per calender sprays with Dithane alone on both cultivars. However, per calender spray with a high rate of Dithane alone compared well with some treatments which included Headline or Quadris on Myles. Almost all other sequences were effective on Myles, but on CDC Yuma the most effective were those that included mostly Headline and in some cases Quadris. In general, at least three sprays to Myles and most treatments with at least four sprays to CDC Yuma reduced blight to less than 50% and also increased yields by up to 84% in Myles and up to 351% in CDC Yuma. The results suggest that there could be a range of different fungicides and sequences one might use to adequately protect chickpea, but this will depend on the registration of products other than Bravo 500

Superconducting Pairing Symmetries in Anisotropic Triangular Quantum Antiferromagnets

Motivated by the recent discovery of a low temperature spin liquid phase in layered organic compound $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$ which becomes a superconductor under pressure, we examine the phase transition of Mott insulating and superconducting (SC) states in a Hubbard-Heisenberg model on an anisotropic triangular lattice. We use a renormalized mean field theory to study the Gutzwiller projected BCS wavefucntions. The half filled electron system is a Mott insulator at large on-site repulsion $U$, and is a superconductor at a moderate $U$. The symmetry of the SC state depends on the anisotropy, and is gapful with $d_{x^2-y^2}+id_{xy}$ symmetry near the isotropic limit and is gapless with $d_{x^2-y^2}$ symmetry at small anisotropy ratio.Comment: 6 pages, 5 figure

Promoting chickpea maturity through fertility management

Non-Peer Reviewe

Chickpea seed yield in response to stubble type and fertility

Non-Peer Reviewe

Adaptation of chickpea to high latitude areas with short growing seasons: biomass and seed yield responses

Non-Peer ReviewedThis study was conducted to determine plant establishment, biomass and seed yield of chickpea under diverse environmental and crop management conditions. Four cultivars were grown on three types of seedbed using N fertilizer rates of 0, 28, 64, 84, and 112 kg N ha-1 with and without Rhizobium inoculant (GR), at six sites in Saskatchewan, Canada. On average, chickpea grown on fallow seedbed produced the highest straw biomass, 5.8 t ha-1, or 28% greater than chickpea grown on barley stubble and 13% greater than being grown on wheat stubble. Similarly, chickpea grown on fallow produced seed yield of 2.5 t ha-1, 22 and 14% greater than chickpea grown on barley and wheat stubble, respectively. The cultivar CDC-Frontier produced biomass of 7.6 t ha-1, 13% greater than CDC-Xena and 7% greater than Amit and CDC-Anna. Increasing N rates from 0 to 112 kg ha-1 without GR increased biomass production and seed yield in a linear relationship with the slopes being 0.556, 0.475, and 0.089 (t ha-1 per kg of N fertilizer) for biomass produced on barley-, wheat-, and fallow-seedbeds, respectively, and the slopes for seed yield being 0.231, 0.226, and 0.055, respectively. CDC-Frontier produced the greatest biomass and seed yield and was the most stable cultivar across the diverse growing environments, whereas CDC-Xena had the lowest productivity with highest variability. This study showed that there was large variability in primary production of chickpea biomass and seed yield in these high latitude areas, but the variability can be minimized by adopting best management practices such as optimizing seedbed conditions, selecting cultivars with high yield potentials, and use of effective N-fixing inoculants