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991.
992.
Calculation of High Frequency Complex Permeability of Carbonyl Iron Flakes in a Nomagnetic Matrix 总被引:1,自引:0,他引:1
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The carbonyl iron flakes are fabricated by high-energy ball milling. The effective permeability is measured and calculated for the composite consisting of flakes embedded in a nonmagnetic matrix. The magnetic flakes with a shape anisotropy and random spatial distribution of normal direction are considered to calculate the complex permeability of magnetic flake materials. Its analytical model is derived from the Landau-Lifshitz-Gilbert equation and Bruggeman 's effective medium theory. The calculated results agree well with the experiment. 相似文献
993.
We propose a non-stationary method to measure the energy relaxation time of Josephson tunnel junctions from microwave enhanced escape phenomena. Compared with the previous methods, our method possesses simple and accurate features. Moreover, having determined the energy relaxation time, we can further obtain the coupling strength between the microwave source and the junction by changing the microwave power. 相似文献
994.
Forcible-Measurement Attack on Quantum Secure Direct Communication Protocol with Cluster State
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The security of the quantum secure direct communication (QSDC) protocol with cluster state is analysed. It is shown that the secret would be partially leaked out when an eavesdropper performs forcible measurements on the transmitted particles. With the help of the result in minimum error discrimination, an upper bound (i.e. 40%) of this leakage is obtained. Moreover, the particular measurements which makes the leakage reach this bound are given. 相似文献
995.
Conductive perovskite BaPb03 (BPO) films as a potential electrode material of PZT capacitors used in ferroelectric random access memory are prepared by rf magnetron sputtering. An x-ray diffractometer and standard four probe method are employed to investigate the dependence of growth conditions on crystal structure and conductivity of BPO films. It is found that BPO films with perovskite phase can be obtained at substrate temperatures above 425℃, and the sample with the lowest resistivity is obtained at 450℃ under pure argon atmosphere. Using this BPO film as electrode, ferroelectric properties of BPO/PZT/BPO and Pt/PZT/BPO sandwiched structures are evaluated. Their remanent polarization and coercive field are 36.6 ℃/cm^2 (81.3 k V/cm) and 36.9℃/cm^2 (89.1 kV/cm), respectively. The coercive field of the former structure is lower than that of the latter, but remanent polarizations are almost the same. In addition, the results imply that BPO electrode is helpful to improve the fatigue resistance of PZT. The reasons are discussed. 相似文献
996.
Self-Injection and Acceleration of Monoenergetic Electron Beams from Laser Wakefield Accelerators in a Highly Relativistic Regime
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H.Yoshitama ;T.Kameshima ;谷渝秋 ;郭仪 ;焦春晔 ;刘红杰 ;彭翰生 ;唐传铭 ;王小东 ;温贤伦 ;温天舒 ;吴玉迟 ;张保汉 ;朱启华 ;黄晓军 ;安维民 ;黄文会 ;唐传祥 ;林郁正 ;王小东 ;陈黎明 ;H.Kotaki ;M.Kando ;K.Nakajima 《中国物理快报》2008,25(8):2938-2941
Self-injection and acceleration of monoenergetic electron beams from laser wakefield accelerators are first investigated in the highly relativistic regime, using 100 TW class, 27 fs laser pulses. Quasi-monoenergetic multi- bunched beams with energies as high as multi-hundredMeV are observed with simultaneous measurements of side-scattering emissions that indicate the formation of self-channelfing and self-injection of electrons into a plasma wake, referred to as a 'bubble'. The three-dimensional particle-in-cell simulations confirmed multiple self-injection of electron bunches into the bubble and their beam acceleration with gradient of 1.5 GeV/cm. 相似文献
997.
Cryptanalysis of Multiparty Quantum Secret Sharing of Quantum State Using Entangled States
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Security of a quantum secret sharing of quantum state protocol proposed by Guo et al. [Chin. Phys. Lett. 25 (2008) 16] is reexamined. It is shown that an eavesdropper can obtain some of the transmitted secret information by monitoring the classical channel or the entire secret by intercepting the quantum states, and moreover, the eavesdropper can even maliciously replace the secret message with an arbitrary message without being detected. Finally, the deep reasons why an eavesdropper can attack this protocol are discussed and the modified protocol is presented to amend the security loopholes. 相似文献
998.
A hypothesis is brought forward that the materials with low propagation loss in both optical and microwave band may exhibit good performance in terahertz (THz) band because THz wave band interspaces those two wave bands. For the purpose-of exploring a kind of low-loss material for THz waveguide, Lu2.1Bi0.9Fe5O12(LuBiIG) garnet films are prepared by liquid phase epitaxy (LPE) method on a gadolinium gallium garnet (GGG) substrate from lead-free flux because of the good properties in both optical and microwave bands. In microwave band, the ferromagnetic resonance (FMR) linewidth of the film 2△H = 2.8-5.1Oe; in optical band, the optical absorption coefficient is 600cm^-1 at visible range and about 100-170cm^-1 when the wavelength is longer than 800nm. In THz range, our hypothesis is well confirmed by a THz-TDS measurement which shows that the absorbance of the film for THz wave is 0.05-0.3 cm 1 and the minimum value appears at 2.3 THz. This artificial ferromagnetic material holds a great promise for magnetic field tunable THz devices such as waveguide, modulator or switch. 相似文献
999.
Passively Q-Switched Quasi-Continuous-Wave Diode-Pumped Intracavity Optical Parametric Oscillator at 1.57
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We report on a passively Q-switched quasi-cw diode-pumped Nd:YAG including an intracavity optical parametric oscillator. The dynamics of this system is described by solving the coupled equations. The effect of the initial transmission of Cr4+:YAG saturable absorber on the signal wave operation is studied. Under optimum conditions, we achieve 2.3mJ energy at 1.57μm wavelength for 40Hz repetition rate. The peak power of the pulses amounts to 0.88MW with the pulse width of 2.6ns. When the Fresnel reflection losses of the filters are taken into account, the pulse energy would be higher than 2.3mJ. To the best of our knowledge, this is the highest pulse energy and peak power for such a type of single resonant quasi-cw diode pumped Nd:YAG/Cr4+:YAG IOPO laser. 相似文献
1000.
Pure cotton low-twist single yarn has good softness, bulkiness, and wearing comfort, but its lower strength makes the yarn break easily during the spinning proc... 相似文献