压电复合材料宽带横波换能器的实验研究

本文用实验方法研究了２－２压电复合材料的厚度切变特性，定性地给出了２－２压电复合材料的性能与ＰＺＴ相体积百分比，以及与共振频率牟关系。并用这种材料作为换能元件，制作出高灵敏度窄脉冲横波换能器。     

3-幂零矩阵的Jordan标准型在GL_n(F)共轭作用下的迷向子群

研究迷向子群的结构是有限域上典型群几何中的一个重要问题.刻画了3-幂零矩阵的Jordan标准型在GLn(F)共轭作用下的迷向子群的结构.     

HL-1装置边缘区的电探针测量

用一个可移动的静电双探针获得了HL-1装置边缘区电子温度T_e,电子密度n_e的时空分布。实验测得孔栏边缘处T_e和n_e。分别约为12eV和3×10~(11)cm~(-3),n_e沿小半径方向的径向梯度约4.7X 10~(11)cm~(-3);在等离子体边缘区,n_e,T_e的e倍衰减特性长度分别约为20mm和27mm,在删削区内,λ_n,λ_T急剧减小。粒子的横向扩散系数与玻姆系数同量级。     

On the stability of a compressible Rivlin's cube made of transversely isotropic material

^** Email: kostas.soldatos{at}nottingham.ac.uk This paper considers a unit cube made of a compressible, transverselyisotropic elastic material, with the direction of transverseisotropy being aligned normal to one pair of the cube's faces,and investigates the stability of a dilatation equilibrium stateof that cube, with respect to superposed pure homogeneous deformationswith principal directions parallel to the cube edges. This dilatation,intermediate equilibrium state (state I) of the cube is assumedattainable in two different ways. Accordingly, in what is termedas the ‘principal stability problem’ under investigation,state I is considered to be that of uniform dilatation, whichis attained upon loading normally and uniformly the oppositefaces of the unit cube with certain pairs of equal and oppositelydirected forces having appropriately selected magnitudes. Inwhat is termed as the ‘modified stability problem’under investigation, the same compressible, transversely isotropicunit cube is loaded uniformly by three identical pairs of equaland oppositely directed forces acting normally to its faces,and, hence, it attains in state I the shape of a certain rectangularparallelepiped. The necessary and sufficient conditions forstability of state I of the cube deformation are obtained inthe form of three inequalities, which are found to hold regardlessof whether the intermediate equilibrium state I is that of uniformdilatation or that of the aforementioned rectangular parallelepiped(non-uniform dilatation). These, however, lead to quite differentspecific results and conclusions when applied in connectionwith, first, the principal and, then, the modified stabilityproblem of a unit cube made of a particular type of a transverselyisotropic extension of the Blatz–Ko (isotropic) material.     

Final state interactions and the transverse structure of the pion using non-perturbative eikonal methods

In the factorized picture of semi-inclusive hadronic processes the naive time-reversal odd parton distributions exist by virtue of the gauge link which renders it color gauge invariant. The link characterizes the dynamical effect of initial/final-state interactions of the active parton due soft gluon exchanges with the target remnant. Though these interactions are non-perturbative, studies of final-state interaction have been approximated by perturbative one-gluon approximation in Abelian models. We include higher-order gluonic contributions from the gauge link by applying non-perturbative eikonal methods incorporating color degrees of freedom in a calculation of the Boer–Mulders function of the pion. Using this framework we explore under what conditions the Boer–Mulders function can be described in terms of factorization of final state interactions and a spatial distribution in impact parameter space.     

Transverse momentum distribution of the Z produced at the Large Hadron Collider and related phenomena

From the recent theoretical result on the production of the Higgs boson at the Large Hadron Collider, it follows that other particles will also be produced with small transverse momentum, of the order of 1 GeV/c$1\text{GeV}/c$. The leptonic decay mode of the Z is especially suited for a first observation of this phenomenon. Other related effects, such as paired jets, are also discussed.     

Phase diagrams of the transverse Ising antiferromagnet in the presence of the longitudinal magnetic field

In this paper we study the critical behavior of the two-dimensional antiferromagnetic Ising model in both uniform longitudinal (H$H$) and transverse (Ω$\Omega$) magnetic fields. Using the effective-field theory (EFT) with correlation in single site clusters we calculate the phase diagrams in the H−T$H-T$ and Ω−T$\Omega -T$ planes for the square lattice. We have only found second order phase transitions for all values of fields and reentrant behavior was not observed.     

Wide-range frequency method to obtain the transverse permeability from impedance measurements

In this work we present a method to obtain the transverse permeability of magnetic materials, valid for both cylindrical and rectangular geometry and a wide frequency range. The principle of this method is based on the dependence of the transverse permeability on the impedance through the skin-depth effect. We also present measurements of the transverse permeability from glass-coated microwires and a comparison with other well-established methods, namely approaches to low and high frequencies. From the complex permeability spectra we can obtain, for example, information about the domain-wall dynamics and the ferromagnetic resonance.     

A note on transverse divergence and taut Riemannian foliations

In this note we give a characterization of taut Riemannian foliations using the transverse divergence. This result turns out to be a convenient tool in the case of some standard examples. Furthermore, we show that a classical tautness result of Haefliger can be obtained in our particular setting as a straightforward consequence. In the final part of the paper we obtain a tautness characterization for transversally oriented foliations with dense leaves.     

Microscopic functional specificity can be predicted from fMRI signals in ventral visual areas

Functional areas specialized for recognition can be activated by a non-preferred stimulus as well as a preferred stimulus. The functional magnetic resonance imaging signals detected in response to different stimuli in an area may have the same or different amplitudes. However, it is uncertain whether the responses originate from the same neuronal populations or heterogeneous ones. To address this concern, we propose a novel method that uses multi-echo echo-planar imaging sequences to evaluate changes in the transverse relaxation profile caused by stimulation. According to this method, the areas related with visual recognition, i.e. fusiform face area and parahippocampal place area, have different transverse relaxation profiles to preferred and non-preferred stimuli, which can be considered as reflecting a difference in neuronal population processing stimuli in those areas. The proposed method can be useful for probing the microscopic functional specificity of brain areas.