Hotspot analysis of COVID-19 infection using mobile-phone location data

Artificial Life and Robotics - Restrictions on outdoor activities are required to suppress the COVID-19 pandemic. To monitor social risks and control the pandemic through sustainable restrictions,...     

Damping properties of thermoplastic-elastomer interleaved carbon fiber-reinforced epoxy composites

The aim of this study is to characterize the damping properties of carbon fiber-reinforced interleaved epoxy composites. Several types of thermoplastic-elastomer films, such as polyurethane elastomers, polyethylene-based ionomers and polyamide elastomers were used as the interleaving materials. The damping properties of the composite laminates with/without the interleaf films were evaluated by the mechanical impedance method. Also, the effects of the lay-up arrangements of the carbon-fiber prepregs on the damping properties of the interleaved laminates were examined. The viscoelastic properties of interleaved polymer films were reflected in the damping properties of the corresponding interleaved laminates. The loss tangent of the interleaf films at the test temperature played an important roll in the loss factor of the interleaved laminates. Also, the stiffness of the films at the resonant frequency of the laminates was another important parameter that controlled the loss factor of the interleaved laminates.     

Piezoelectric properties of vinylidene fluoride oligomer for use in medical tactile sensor applications

The piezoelectric effect of vinylidene fluoride (VDF) oligomer was evaluated with respect to its medical use as a new tactile sensor. VDF oligomer is a new substance that has a smaller number of VDF units and a lower molecular weight than poly(vinylidene fluoride) (PVDF); among the organic ferroelectrics, it has the largest reported remanent polarization. In this work, the performance of a prototype sensor device based on this material was evaluated. The piezoelectric coefficient of VDF oligomer was found to be greater than that of P(VDF/TrFE) copolymer; a film composed of VDF oligomer was thin and uniform. Based on the experimental results, possible applications of VDF oligomer in medical tactile sensors are discussed. This study confirms that VDF oligomer is a promising ferroelectric material for use in tactile sensors.     

Study on discrete adiabatic quantum computation in 3-SAT problems

The quantum adiabatic algorithm is a method of solving computational problems by evolving the ground state with a slowly varying Hamiltonian to reach the required output state. This article proposes a new variation on the method for the phase functions of the adiabatic quantum algorithm, the quadric variation method. Experiments were carried out to solve the 3-SAT problem with the discrete adiabatic quantum algorithm to compare the performance of the proposed formulation of the quadric variation method with the previously proposed linear and cubic methods.     

Anomalous specific heat of the La-Ge system

The specific heat of the orthorhombically distorted -ThSi₂-type La-Ge intermetallic compound system has been measured in the temperature range 0.07 T 10 K. An anomalous behavior of the lattice part of the specific heat has been discovered. The specific heat data are analyzed and discussions are given, with particular attention to the superlattice structure observed in these compounds.     

Thermal Cyclic Fatigue Behavior of Porous Ceramics for Gas Cleaning

The thermal shock fatigue resistance of cordierite and SiC filters with a mullite filtration layer was evaluated under simulated reverse cleaning conditions. O-ring specimens were thermally shocked by cyclically blowing cold air outward through them while they were exposed to high-temperature flue gas. The calculated values of the tangential tensile stresses induced by the temperature differences between the inner and outer surfaces were found to be largest at the inner surfaces. It was also found that the elastic modulus and the thermal expansion coefficient of the filters affect the magnitude of the thermal stresses more than the thermal diffusivity and thermal transfer area, which were directly related to the microstructure of the filters. Failure of both filters is believed to have initiated at the inner subsurfaces because of the effects of thermal shock. The thermal shock fatigue lifetimes increased as thermal stresses decreased. The fatigue parameters for the SiC and cordierite filters were found to be 41 and 22, respectively. These parameters probably vary over different operating temperature ranges, especially in the case of SiC filters, where changes in their composite microstructures affect their high-temperature strength.     

Analyses of Instability in Mobile Cranes due to Ground Penetration by Outriggers

This study focuses on the phenomenon of ground instability causing mobile cranes to overturn. Four outriggers usually support a mobile crane in order to restrict pitching during hoisting operations. Nevertheless, the crane may become quite unstable if the outriggers should happen to sink into the bearing ground. In this paper, various types of analysis, including experiments, were performed in order to investigate the influence of ground penetration by outriggers on the stability of mobile cranes. Through study of the results of experimentation and simulation, it has been clarified that mobile cranes become highly unstable as a result of rapid penetration. It was found that an index of relative instability had a linear relationship to the common logarithm of an index for brittle failure as derived from the load–settlement curve for ground penetration. Finally, a method of evaluating the risk of mobile-crane overturning is proposed by using the maximum value of both the supporting surface’s failure risk and the kinetic risk due to ground penetration.     

Excellent compositional homogeneity in In0.3Ga0.7As crystals grown by the traveling liquiduszone (TLZ) method

The influence of convection in a melt on the compositional homogeneity of the TLZ-grown In_0.3Ga_0.7As crystals has been investigated by growing crystals with various dimensions on the ground. Excellent compositional homogeneity such as 0.3 plus or minus 0.01 in InAs mole fraction for a distance of 25 mm was obtained when the melt diameter was limited to 2 mm and convective flow in the melt was suppressed. On the other hand, when the crystal diameter was increased to 10 mm, both axial and radial compositional homogeneity was deteriorated due to convection in the melt. Comparing with the numerical simulation, convective flow velocity less than 1.4 mm/h may be sufficient for growing homogeneous crystals and it is not so difficult to suppress convective flow velocity below 1.4 mm/h for 10 mm diameter crystals in microgravity. Therefore, larger homogeneous In_0.3Ga_0.7As crystals are expected to be grown by the TLZ method on board the International Space Station.     

具有力传感器的纳米加工探针的设计

给出了一种用于复杂表面形状精密纳米加工的探针装置．该探针由一个高速可控的金刚石切割单元（FTC单元）和一个高灵敏度的压电式力传感器组成．而FTC单元由一个单点金刚石切割工具和一个压电陶瓷晶体（PZT）驱动器构成．压电陶瓷晶体（PZT）驱动器可对与切削量相对应的金刚石工具的Z向位置进行高速控制,从而实现加工复杂表面形状的目的．加工中的切削力是反映切削进程的重要指标,可由联结于FTC单元的高灵敏度力传感器进行测量．比对了用于联结力传感器和FTC单元的两种设计方法．     

Design of a small‐size interlocking system with high availability

An interlocking system consists of an interlocking logical unit and a power controlling unit. After this logical unit calculates the relationship among the train position, the rail shifting position, and the signal, it decides the aspect of the signal. The power controlling unit supplies electrical power to the switch motor and the signal light according to the decision of the logical unit. This paper proposes a small‐sized interlocking system which uses a triplex redundant off‐the‐shelf controller with fail‐safe checker as an interlocking logical unit. A majority voting circuit ensures the safety of parallel output from the interlocking logical unit. This circuit satisfies the condition of total self‐checking (of D.A. Anderson) and also the condition of high availability. In other words, no single fault ever leads to a hazardous state and this circuit ensures safety after single fault occurrence. © 1999 Scripta Technica, Electr Eng Jpn, 128(2): 63–73, 1999