Symmetric duality for a class of nondifferentiable multi-objective fractional variational problems

AbstractWe introduce a symmetric dual pair for a class of nondifferentiable multi-objective fractional variational problems. Weak, strong, converse and self duality relations are established under certain invexity assumptions. The paper includes extensions of previous symmetric duality results for multi-objective fractional variational problems obtained by Kim, Lee and Schaible [D.S. Kim, W.J. Lee, S. Schaible, Symmetric duality for invex multiobjective fractional variational problems, J. Math. Anal. Appl. 289 (2004) 505–521] and symmetric duality results for the static case obtained by Yang, Wang and Deng [X.M. Yang, S.Y. Wang, X.T. Deng, Symmetric duality for a class of multiobjective fractional programming problems, J. Math. Anal. Appl. 274 (2002) 279–295] to the dynamic case

Effect of Na doping on flux pinning of YBa1.9Na0.1Cu3O7-d

We have prepared Na-doped YBa2Cu3Oy (YBa1.9Na0.1Cu3Oy +40mol%Y211) (YBNCO) and Na-free YBa2Cu3Oy (YBCO) samples by the Melt-Textured Growth (MTG) method to study the effect of doped Na ion on flux pinning. The ac susceptibility curves (acs) as well as the hysteresis loops were measured for the samples. Then the effective pinning energy (U(T,Hdc,J)), irreversibility line (Hirr(T)) and critical current density (jc(Hdc)) were determined, where T, Hdc and J are temperature, dc magnetic field and current density, respectively. We found that, with Na doping, the Hirr(T) line shifted to lower temperature while the Jc(Hdc) and U(T,Hdc,J) became smaller. It indicates that the Na ions play a negative role in the flux pinning of YBCO. The appearance of the second peak in the Jc(Hdc) curves and the enhancement of anisotropy in YBNCO further support this finding.Comment: 7 pages, 7figures. Submited to Physica.

Metastable behavior of vortex matter in the electronic transport processes of homogenous superconductors

We study numerically the effect of vortex pinning on the hysteresis voltage-temperature (V-T) loop of vortex matter. It is found that different types of the V-T loops result from different densities of vortex pinning center. An anticlockwise V-T loop is observed for the vortex system with dense pinning centers, whereas a clockwise V-T loop is brought about for vortices with dilute pinning centers. It is shown that the size of the V-T loop becomes smaller for lower experimental speed, higher magnetic field, or weak pinning strength. Our numerical observation is in good agreement with experiments

Force measurement on coupled flapping flags in uniform flow

An experimental study on the coupled flapping of two identical flags arranged in parallel, tandem, and staggered positions in uniform flow was conducted in a wind tunnel. The dynamic characteristics of each flag were measured using an in-house designed balance and the flapping modes were analyzed through a high-speed video recording technique and a "Spatio-Temporal Evolution" software. For the side-by-side arrangement, the dependences of the kinematic and dynamic parameters on the flow speed and on the mutual distance were observed. The results indicated that the coupling motion and dynamics of two parallel flags in uniform flow were mainly affected by their mutual position. Significant drag reductions were observed when the flags flapped in the in-phase mode for a relatively small separation. For two flags in tandem arrangement, both the upstream and downstream flags experienced a drag reduction compared to the scenario of a single flag in the same flow. Especially, for relatively large separation the upstream flag had a smaller drag coefficient than that of the downstream one. For very small separation, the drag coefficient of the upstream flag was larger than that of the downstream one. Finally, for two flags arranged in a staggered configuration, an anomalous drag distribution was found. This work provides valuable experimental data and casts insight into the coupling mechanism of multiple flexible structures in an air flow

Testing for Stock Market Contagion: A Quantile Regression Approach

__Abstract__ Regarding the asymmetric and leptokurtic behavior of financial data, we propose a new contagion test in the quantile regression framework that is robust to model misspecification. Unlike conventional correlation-based tests, the proposed quantile contagion test allows us to investigate the stock market contagion at various quantiles, not only at the mean. We show that the quantile contagion test can detect a contagion effect that is possibly ignored by correlation-based tests. A wide range of simulation studies show that the proposed test is superior to the correlation-based tests in terms of size and power. We compare our test with correlation-based tests using three real data sets: the 1994 Tequila crisis, the 1997 Asia crisis, and the 2001 Argentina crisis. Empirical results show substantial differences between two types of tests

Improved interfacial and electrical properties of GaAs metal-oxdiesemiconductor capacitors with HfTiON as gate dialectric and TaON as Passivation interlayer

published_or_final_versio

In-Plane Magnetic Anisotropy In RF Sputtered Fe-N Thin Films

We have fabricated Fe(N) thin films with varied N2 partial pressure and studied the microstructure, morphology, magnetic properties and resistivity by using X-ray diffraction, atomic force microscopy, transmission electron microscopy, vibrating-sample magnetometer and angle-resolved M-H hysteresis Loop tracer and standard four-point probe method. In the presence of low N2 partial pressure, Fe(N) films showed a basic bcc a-Fe structure with a preferred (110) texture. A variation of in-plane magnetic anisotropy of the Fe(N) films was observed with the changing of N component. The evolution of in-plane anisotropy in the films was attributed to the directional order mechanism. Nitrogen atoms play an important role in refining the a-Fe grains and inducing uniaxial anisotropy.Comment: 11 pages, 6 figure

The effects of local voids and imperfections of surrounding rock on the performance of existing tunnel lining

Local voids and imperfections may exist around the tunnel due to reasons such as inadequate back infill behind the lining, insufficient local lining thickness, ground water erosion, and other imperfect construction related activities. Such local voids and imperfections generally will lead to local contact loss and discontinuity in the ground-lining interaction. This paper evaluates the effect of local voids and imperfections developing around the tunnel vault area on the mechanical performance of tunnel lining. Based on field investigation results, a series of voids and imperfections with different geometries are defined to reflect cases resulting from different causes. Numerical parametric analyses were performed to investigate how those voids and imperfections influence the internal force and the safety factor of the lining, and the reinforced concrete lining were modelled with the smeared crack model to examine the development of cracking directions and patterns. Furthermore, the numerical approach was verified by comparing with field investigations and measurements. This study aims to investigate the most unsafe situation due to local voids and imperfections around the tunnel, and the modelled cracking feature shows a way to preliminary evaluate the possible local voids and imperfections behind tunnel lining based on field observation

Comparison of Vlasov-Uehling-Uhlenbeck model with 4 π Heavy Ion Data

Streamer chamber data for collisions of Ar + KCl and Ar + BaI2 at 1.2 GeV/nucleon are compared with microscopic model predictions based on the Vlasov-Uehling-Uhlenbeck equation, for various density-dependent nuclear equations of state. Multiplicity distributions and inclusive rapidity and transverse momentum spectra are in good agreement. Rapidity spectra show evidence of being useful in determining whether the model uses the correct cross sections for binary collisions in the nuclear medium, and whether momentum-dependent interactions are correctly incorporated. Sideward flow results do not favor the same nuclear stiffness parameter at all multiplicities