Transition from negative magnetoresistance behavior to positive behavior in Co\u3csub\u3e20\u3c/sub\u3e (Cu\u3csub\u3e1-x\u3c/sub\u3eGe\u3csub\u3ex\u3c/sub\u3e)\u3csub\u3e80\u3c/sub\u3e ribbons

We report a transition of the giant magnetoresistance (GMR) behavior in nanocrystalline Co20 (Cu1-xGex)80 ribbons from negative to positive, as the semiconductor Ge substitutes for the Cu matrix. The growth of the hexagonal Co3Ge2 compound leads to a change of the physical origin of the GMR. The normal spin-dependent transport behavior in the CoCu granular system evolves into Coulomb blockade behavior of electronic tunneling in ribbons with a Co/Co3Ge2/Co junctionlike configuration

Structure and magnetic properties of sputtered (Nd,Dy)(Fe,Co,Nb,B) \u3csub\u3e5.5\u3c/sub\u3e/M (M = FeCo,Co) multilayer magnets

The magnetic properties of nanocomposite multilayer magnets of the (Nd,Dy)(Fe,Co,Nb,B) 5.5/M (M = Co,FeCo) on Ti-buffered Si substrates have been investigated. X-ray diffraction results reveal that the Nd2Fe14B-type phase in almost all the films is randomly oriented. Different thickness x (nm) for Co layers and y (nm) for FeCo layers were adopted in the multilayers. It is found that high remanence is achieved in the nanocomposite multilayer films consisting of the Nd2Fe14B-type phase and soft magnetic phase for Co with 6≥x≥4 and for FeCo with 10≥y≥6. The enhancement of the remanence in the nanocomposite multilayer films is attributed to the exchange coupling between the magnetically soft and hard phases. Increasing the soft magnetic components results in a continuously decreasing coercivity

Structure and magnetic properties of sputtered (Nd,Dy)(Fe,Co,Nb,B) \u3csub\u3e5.5\u3c/sub\u3e/M (M = FeCo,Co) multilayer magnets

The magnetic properties of nanocomposite multilayer magnets of the (Nd,Dy)(Fe,Co,Nb,B) 5.5/M (M = Co,FeCo) on Ti-buffered Si substrates have been investigated. X-ray diffraction results reveal that the Nd2Fe14B-type phase in almost all the films is randomly oriented. Different thickness x (nm) for Co layers and y (nm) for FeCo layers were adopted in the multilayers. It is found that high remanence is achieved in the nanocomposite multilayer films consisting of the Nd2Fe14B-type phase and soft magnetic phase for Co with 6≥x≥4 and for FeCo with 10≥y≥6. The enhancement of the remanence in the nanocomposite multilayer films is attributed to the exchange coupling between the magnetically soft and hard phases. Increasing the soft magnetic components results in a continuously decreasing coercivity

Multi-neutron transfer coupling in sub-barrier 32S+90,96Zr fusion reactions

The role of neutron transfers is investigated in the fusion process below the Coulomb barrier by analyzing 32S+90Zr and 32S+96Zr as benchmark reactions. A full coupled-channel calculation of the fusion excitation functions has been performed for both systems by using multi-neutron transfer coupling for the more neutron-rich reaction. The enhancement of fusion cross sections for 32S+96Zr is well reproduced at sub-barrier energies by NTFus code calculations including the coupling of the neutron-transfer channels following the Zagrebaev semiclassical model. We found similar effects for 40Ca+90Zr and 40Ca+96Zr fusion excitation functions.Comment: Minor corrections, 11 pages, 4 figures, Fusion11 Conference, Saint Malo, France, 2-6 mai 201

Time and Frequency Domain Simulation, Measurement and Optimization of Log-Periodic Antennas

Log-periodic antenna is a special antenna type utilized with great success in many broadband applications due to its ability to achieve nearly constant gain over a wide frequency range. Such antennas are extensively used in electromagnetic compatibility measurements, spectrum monitoring and TV reception. In this study, a log-periodic dipole array is measured, simulated, and then optimized in the 470–860 MHz frequency band. Two simulations of the antenna are initially performed in time and frequency domain respectively. The comparison between these simulations is presented to ensure accurate modelling of the antenna. The practically measured realized gain is in good agreement with the simulated realized gain. The antenna is then optimized to concurrently improve voltage standing wave ratio, realized gain and front-to-back ratio. The optimization process has been implemented by using various algorithms included in CST Microwave Studio, such as Trusted Region Framework, Nelder Mead Simplex algorithm, Classic Powell and Covariance Matrix Adaptation Evolutionary Strategy. The Trusted Region Framework algorithm seems to have the best performance in adequately optimizing all predefined goals specified for the antenna

Zircon records of Miocene ultrapotassic rocks from southern Lhasa subterrane, Tiben Plateau

Zircons entrained in mantle-derived magmas offer a prime opportunity to reveal cryptic magmatic episodes in the deep crust. We have investigated zircons from mantle-derived ultrapotassic veins in the Xuena area, southern Lhasa subterrane. Zircons in the Xuena ultrapotassic rocks reveal four major magmatic pulses around <100Ma, 300 ~ 400Ma, 450 ~ 500Ma, and 700 ~ 850Ma. The high U / Yb ratios and low Y contents of these zircons demonstrate their continental origin. Cenozoic-Mesozoic and Late Paleozoic magmatism have been widely identified from the southern Lhasa subterrane, suggesting the contribution from overlying juvenile crust. But similar Proterozoic-Early Paleozoic age distributions (450 ~ 500Ma and 700 ~ 850Ma) between these zircon xenocrysts and those dating records in the Himalayan orogenic belt corroborate the input from underthrusted Indian continental crust. Furthermore, the Increasing (Dy / Yb) N ratio since ~ 60 Ma zircon and Rapid Decreasing epsilon Hf ( t ) values, from + 10 ~ + 5 to -10 ~ -25, are Interpreted to reflect Significant and progressive Crustal Thickening in Response to India-Asia convergence and the contribution from subducted Indian continental crust to postcollisional magmatism in the southern Lhasa sub-terrane

A self-consistent method to analyze the effects of the positive Q-value neutron transfers on fusion

AbstractConsidering the present limitation of the need for external parameters to describe the nucleus–nucleus potential and the couplings in the coupled-channels calculations, this work introduces an improved method without adjustable parameter to overcome the limitation and then sort out the positive Q-value neutron transfers (PQNT) effects based on the CCFULL calculations. The corresponding analysis for Ca+Ca, S,Ca+Sn, and S,Ca+Zr provides a reliable proof and a quantitative evaluation for the residual enhancement (RE) related to PQNT. In addition, the RE for S32,Ca40+Zr94 shows an unexpected larger enhancement than S32,Ca40+Zr96 despite the similar multi-neutron transfer Q-values. This method should rather strictly test the fusion models and be helpful for excavating the underlying physics

Flexural Fracture Toughness and First-Crack Strength Tests of Steel Fiber-Silica Fume Concrete and Its Engineering Applications

The effect of a steel fiber and silica fume on the first-crack strength and the flexural toughness of concrete is evaluated. The ten sets of specimens with a steel fiber content of 0, 40, 50, and 60 g/m³ and steel fiber types of wave shear and straight shear types with and without a silica fume content of a 10% replacement of the cement weight were tested. The results show that the combined effect of silica fume and steel fiber improve the first-crack load and deflection of specimens to a certain degree and increase the flexural fracture toughness of specimens greatly. In the strengthening effect of steel fiber silica fume concrete, the steel fiber is of first importance, while silica fume is an auxiliary component. The wet steel fiber-silica fume shotcrete support for controlling the surrounding rock mass can provide the whole supporting effect of the anchor mesh shotcrete.Выполнена оценка влияния стального волокна и кремнеземной пыли на прочность бетона при появлении первой трещины и вязкость разрушения при изгибе. Выполнены испытания 10 серий образцов с содержанием стального волокна 0, 40, 50, 60 г/м³, использовано стальное волокно различных типов без содержания кремнеземной пыли и с ее содержанием на уровне 10% замещения веса цемента. Показано, что совместное использование кремнеземной пыли и стального волокна повышает допустимую нагрузку образования первой трещины и прогиба образцов, а также вязкость разрушения при изгибе. Установлено, что упрочнение сталефибробетона с добавками кремнеземной пыли определяется содержанием стального волокна, а кремнеземная пыль является вспомогательным компонентом. Опора из смеси сталефиброторкретбетона с содержанием кремнеземной пыли, обеспечивающая контроль окружающего скального массива, усиливает общий несущий эффект анкерной структуры