Study of a high-dimensional chaotic attractor

The nature of a very high-dimensional chaotic attractor in an infinite-dimensional phase space is examined for the purpose of studying the relationships between the physical processes occurring in the real space and the characteristics of high-dimensional attractor in the phase space. We introduce two complementary bases from which the attractor is observed, one the Lyapunov basis composed of the Lyapunov vectors and the another the Fourier basis composed of the Fourier modes. We introduce the exterior subspaces on the basis of the Lyapunov vectors and observe the chaotic motion projected onto these exteriors. It is shown that a certain statistical property of the projected motion changes markedly as the exterior subspace goes out of the attractor. The origin of such a phenomenon is attributed to more fundamental features of our attractor, which become manifest when the attractor is observed from the Lyapunov basis. A counterpart of the phenomenon can be observed also on the Fourier basis because there is a statistical one-to-one correspondence between the Lyapunov vectors and the Fourier modes. In particular, a statistical property of the high-pass filtered time series reflects clearly the difference between the interior and the exterior of the attractor.     

Dynamic and subjective responses of seated subjects exposed to simultaneous vertical and fore-and-aft whole-body vibration: The effect of the phase between the two single-axis components

Subjective and dynamic responses of seated subjects exposed to simultaneous vertical and fore-and-aft sinusoidal whole-body vibration were investigated. The effect of the phase difference between the vertical and the fore-and-aft vibration on the responses was of a particular interest in this study. Fifteen subjects were exposed to dual-axis vibrations at six frequencies (2.5-8 Hz) and at eight phases between the two single-axis components (0-315°). The magnitude of vibration in each axis was constant at 0.7 m s⁻² rms. Discomfort caused by vibration was measured by the method of magnitude estimation. The motion of the body were measured at the head and three locations along the spine with accelerometers attached to the body surface. The most significant effect of the phase between the two single-axis components on the discomfort was observed at 5 Hz: about 40% difference in the median discomfort estimate caused by changing the phase. The transmissibilities from vertical seat vibration to vertical motions of the spine varied from 0.5 to 2.0 by changing the phase between the two single-axis components at frequencies from 2.5 to 5 Hz. The effect of the phase observed in the dynamic response was not predicted by the superposition of the responses to each single-axis vibration. The discomfort caused by the dual-axis vibration tended to be correlated better with the combinations of the dynamic responses measured in the two axes than with the dynamic responses in a single axis.     

Mössbauer studies of mixed-valence spin-crossover iron complexes with a hexadentate tripod ligand

The spin-crossover behaviors of mixed-valence iron compounds [Fe^IIH₃L][Fe^IIIL](NO₃)₂ (1) and [Fe^IIH₃L^Me][Fe^IIIL^Me](NO₃)₂ (2) have been investigated by ⁵⁷Fe Mössbauer spectroscopy, where H₃L is a hexadentate N₆ tripod ligand containing three imidazole groups and H₃L^Me is its 2-methylimidazole derivative. Deconvolution analyses of the Mössbauer spectra revealed that a two-step SCO (LS Fe^II–LS Fe^III→HS Fe^II–LS Fe^III→HS Fe^II–HS Fe^III) proceeds in each compound on elevating the temperature. Compound 2 exhibited lower spin-transition temperatures than 1. “Frozen-in effect” was observed below 120 and 50 K for 1 and 2, respectively.     

STF数字微波低电平系统研究

STF是KEK为国际直线对撞机(ILC)建立的试验装置. 在STF中, 数字微波低电平系统用于控制超导腔的RF相位和幅度. 在没有实际腔运行的情况下, 设计了一个基于FPGA技术的实时超导腔模拟器, 用于测试微波低电平系统的硬件和算法. 超导腔的数字控制器用FPGA实现, 其中采用了PI反馈控制和前馈控制算法. 测试表明, 超导腔模拟器和控制器都工作良好, 可用于STF微波低电平系统的进一步开发.     

Signal measurement system for intra-body communication using optical isolation method

In this paper, we describe an induced signal measurement on the human body for developing a high-performance transceiver of an intra-body communication system. It is important to isolate awearable transceiver from an electrical instrument for precise measurement. We have developed a probe system using an optical isolation method including a laser diode, photo-diode, and optical fiber. The probe system can be successfully applied to the precise measurement of a receiving signal power at a wearable transceiver. We verify that the experimental results agree with the simulation results based on our previous channel model of intra-body communication.