Topological design considering flexibility under periodic loads

Topology optimization has been extensively considered to design the structural configuration for the stiffness maximization and the eigenfrequency maximization. In this paper, we construct a topology optimization method implementing flexibility with the time-periodic loading condition. First, the flexibility in the dynamic periodic loading is formulated using the mutual energy concept. Second, the multi-optimization problem is formulated using a new multi-objective function in order to obtain an optimal solution incorporating both flexibility and stiffness. Next, the topology optimization procedure is developed using the homogenization design method. Finally, some examples are provided to confirm the optimal design method presented here. Received January 18, 1999     

A study of hypervelocity impact on cryogenic materials

This paper reports a result of hypervelocity impact experiments on cryogenically cooled aluminum alloys and a composite material. Experiments are carried out on a target palate at 122 K. Aluminum spheres at 1.95 km/s in 50 kPa air were impinged against the target plate at cryogenic temperature and the result was compared with room temperature target plates. Hypervelocity impact (HVI) processes were visualized with shadowgraph arrangement and recorded with high-speed video camera and to ensure the temperature dependence we compared HVI tests with metal target plates with AUTODYN 2D and SPH numerical simulations. We found that cryogenic impacts created slight differences of impact damage from room temperature ones, i.e., the shape and averaged diameters of HVI crater holes were less at cryogenic impacts.     

Activities of Phosphorus in Copper‐Iron Liquid Alloys Saturated with Copper‐Iron Solid Solutions

In order to determine the activities of phosphorus and iron in liquid {Cu‐Fe‐P} alloys, the two coexisting phases of liquid {Cu‐Fe‐P} alloys + <Cu‐Fe‐P> solid solutions were brought into equilibrium with a mixture of Al₂O₃ + AlPO₄ + Fe_xAl₂O₄ at temperatures of 1416K and 1526K. The oxygen partial pressures were measured with the aid of a solid‐oxide galvanic cell of the type: (+)Mo / Mo + MoO₂/ ZrO₂(MgO) / {Cu‐Fe‐P} + <Cu‐Fe‐P> + <Al₂O₃> + <AlPO₄> + <FeAl₂O₄> / Fe(‐) The equilibrium reactions underlying the experiments can be expressed by 2[P]_cu + (5/2) (O₂) + <Al₂O₃> = 2 <AlPO₄> and x[Fe]_Cu + (1/2) (O₂) + <Al₂O₃> = <Fe_xAl₂O₄> The Henrian activity coefficient referred to 1 wt pct solution in pure liquid copper could be well expressed by the formula log f_P° = (4.46±0.40) ‐ (8.67±0.59)/(T/K). The iron activities referred to pure solid iron could be formulated as log a_Fe =‐ (0.37 ± 0.12) + (500 ±200) /(T/K).     

Blind source extraction of long-term physiological signals from facial thermal images

The amount of mental work using information equipment has been increasing because of a rapid growth of an information society. Accumulation of short-term mental work can cause various stresses and a disturbance of circadian rhythm and lead to fatigue, anxiety, and distraction. Estimation and understanding the physiopsychological states is desired for decreasing or controlling stresses to maintain health. There have been several investigations on the assessment of short-term physiopsychological states using infrared thermography. However, the method has been used rarely for assessing long-term physiopsychological states. In the present study, extraction of independent components related to long-term physiological signals is attempted by applying independent component analysis to facial thermal images obtained over 6 months (July–December). Furthermore, multiple regression analysis is attempted to create psychological model by facial thermal images. As the result, extracted independent components are shown to represent the strong features in nasal, mouth, cheek, eyebrow, and forehead regions. Attempting multiple regression analysis, features in nasal and mouth regions contributed to depression or dejection mood, features in cheek, eyebrow and forehead regions contributed to fatigue and features in tip of nasal, eyebrow and mouth regions contributed to state anxiety.     

Physics‐based model of lithium‐ion batteries running on a circuit simulator

The authors developed a physics‐based equivalent circuit model of a lithium‐ion battery (LIB) whose parameters are continually updated, reflecting the theoretical calculation results of the Butler‐Volmer equation, diffusion equations of the lithium‐ion and lithium, and Nernst equations of the liquid and solid phases. The developed model was applied to the charge/discharge simulations of an LIB, and the experimental and simulated results of constant current discharges and pulsed‐charge/discharge were found to be in excellent agreement. In particular, using the developed model, analyzing transient responses of the LIB derived from the transition of the electric double layer charging to the electrode reaction is possible. These results demonstrate that the electrochemical performance of an LIB can be calculated on a circuit simulator using the developed model.