Effect of induced shielding current transmission in longitudinal direction on levitation force of melt grown single-domain YBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7−<Emphasis Type="Italic">x</Emphasis></Subscript> cylindrical superconductor

A novel layer deletion method is used to experimentally investigate the effect of induced shielding current transmission (ISCT) in the longitudinal direction on the levitation force of a single-domain YBa₂Cu₃O_7−x (YBCO) cylindrical superconductor (ϕ30×7 mm). In the experiment the sample was gradually sliced into two equal sheets, at the middle height along a diameter with 5 mm every step. The experimental results show that the levitation force is closely related with the ISCT in the longitudinal direction. Any layer deletion, even a small piece of layer deletion can reduce the levitation force of the sample. After the whole layer was deleted the levitation force can diminish about 50%. It is also found that the levitation force is directly proportional to the effective factor of surface area, which is equal to the top surface area divided by the total surface area parallel to the top surface of the sample.     

Possible triggering of solar activity to big earthquakes (<Emphasis Type="Italic">Ms</Emphasis>≥8) in faults with near west-east strike in China

This paper studies the relationship between solar activity and big earthquakes (Ms≥8) that occurred in China and western Mongolia. It is discovered that the occurrence dates of most of the big earthquakes in and near faults with west-east strike are close to the maximum years of sunspot numbers, whereas dates of some big earthquakes which are not in such faults are not close to the maximum years. We consider that it is possibly because of the appearance of many magnetic storms in the maximum years of solar activity. The magnetic storms result in anomalies of geomagnetic field and then produce eddy current in the faults gestating earthquake with near west-east strike. Perhaps the gestated big earthquakes occur easily since the eddy current heats the rocks in the faults and therefore decreases the shear resistant intensity and the static friction limit of the rocks.     

Nonlinear Response of the Semiconductor Laser with Pump Current Modulation

The influence of tuning the lasing monochromatic radiation frequency _g within the amplification band on the nonlinear response of the semiconductor laser with harmonic modulation of pump current is investigated theoretically. It is established that the principal features of the behavior of the nonlinear amplitude-detuning characteristic (ADC) are determined by the relation between the current modulation frequency _m and the main resonance frequency of the laser _r. If _{m r}, then with increase in _g the response decreases monotonically mainly due to the decrease of its dynamic component. The exception is provided by the spectral regions where peaks on the ADC appear because of the explicitly nonlinear lasing regimes (period doubling, chaos, etc.) When _m < _r, the resonance conditions for induced oscillations are satisfied only for definite spectral intervals within the amplification band and a dip appears on the low-frequency side of the ADC. With decreasing _m, the dip boundary shifts to a more high-frequency region of the band corresponding to smaller local resonance frequencies. The peaks on the ADC corresponding to the radiation period doubling shift to the region of smaller values of _g on increase in _m.     

Green currents for holomorphic automorphisms of compact Kähler manifolds

Let be a holomorphic automorphism of a compact Kähler manifold of dimension . We study the convex cones of positive closed -currents , which satisfy a functional relation

1,\end{displaymath}">

and some regularity condition (PB, PC). Under appropriate assumptions on dynamical degrees we introduce closed finite dimensional cones, not reduced to zero, of such currents. In particular, when the topological entropy of is positive, then for some , there is a positive closed -current which satisfies the relation

Moreover, every quasi-p.s.h. function is integrable with respect to the trace measure of . When the dynamical degrees of are all distinct, we construct an invariant measure as an intersection of closed currents. We show that this measure is mixing and gives no mass to pluripolar sets and to sets of small Hausdorff dimension.

     

Parametric study of 2D potential structures induced by RF sheaths coupled with transverse currents in front of ICRH antenna

Hot-spot formation on the corners of the ICRH antenna can be explained by high DC potential structures, which accelerate ion fluxes and generate strong convective fluxes to the antenna surface. This comes from RF sheaths at the end of open magnetic lines, which rectify RF potential resulting from parallel electric fields. As these electric fields are not homogeneous in front of the antenna, transverse potential gradients generate transverse polarization currents which modify the potential structure. These potentials are studied with a simple flux-tube model and then a 2D-fluid model was elaborated to obtain analytical expressions for rectified potential with respect to these transverse currents. We compare them to numerical results coming from a 2D-fluid code executed in a poloidal plane in front of the antenna. Then we build a potential peak criterion to determine the peaking of DC-potential structures for typical parameters in Tore Supra. Finally, current interaction between different magnetic line lengths is approached.Presented at the Workshop Electric Fields Structures and Relaxation in Edge Plasmas, Nice, France, October 26–27, 2004.     

Synthesis of transparent BaTiO3 nanoparticle/polymer composite film using DC field

Transparent BaTiO₃ nanoparticle/polymer composite films were synthesized from titanium-organic film and barium ion in aqueous solution under direct current (DC) field. Titanium-organic precursor was synthesized from titanium isopropoxide, acetylacetone and methacrylate derivative. The UV treatment was effective to increase the anti-solubility of the titanium-organic film during DC processing. BaTiO₃ nanoparticles were crystallized in the precursor films on stainless substrates without high temperature process, as low as 40°C. The crystallite size of BaTiO₃ increased with increasing reaction temperature from 40 to 50 °C at 3.0 V/cm. BaTiO₃ nanoparticles also grew in size with increasing reaction time from 15 min to 45 min at 3.0 V/cm and 50 °C. Transparent BaTiO₃ nanoparticle/polymer films were synthesized on stainless substrates at 3.0 V/cm and 50°C for 45 min.     

基于多值逻辑的 D/A转换器 分流电阻网络研究

本文通过对 D /A转换器表示的分析 ,用电流分流方法解释了二值 D /A转换器使用电阻网络的 物理实现 ,并在此基础上提出了四值 D /A转换器分流电阻网络 .该分流电阻网络在使用四值信号译码 的情况下将回到二值 D /A转换器.然而 ,这种基于多值逻辑的设计将导致一种新颖的 Π型电阻转换网 络 ,该网络比传统的 T 型电阻网络节省四分之一电阻数量 ,并可保证较高的转换精度.     

聚变装置中真空室上涡流的分析

本文研究了聚变装置真空室上的涡流问题,将真空室上的涡流看作面电流密度并定义一矢势的法向分量来描述它。详细地叙述了求解真空室上感应涡流的计算方法,对HTU托卡马克实验装置真空室上涡流的大小、分布形式及衰减情况进行了分析。     

KLY—1低能宽束离子源的研制

本文简介了KLY-1低能宽束离子源的结构,给出了物理设计的主要公式和调试实验的结果。对于氩离子束,在离子能量为4keV,距引出电极24cm处的5cm直径的靶上,测得最大氩离子流为45mA,束流不均匀性优于±25％。     

Electrodeposition of hafnium from the aqueous bath

A method is described for electrodepositing¹⁸¹Hf from urea-oxalate aqueous bath. The optimum conditions were determined by studying the effects of current density, time of deposition and the cathode metals. More than 80% of¹⁸¹Hf is deposited on a nickel cathode in one hour.