Identification of Human Operations Using Data Clustering and its Applications to Automation

Some human operations are realized by the combination of continuous behaviors and logical judgment. Such a system is called a hybrid dynamical system (HDS). In this study, we consider a driving task as an HDS. Then, we identify the task using the clustering method, which is one of the methods used to identify an HDS. In addition, we apply the identified model to an automatic driving system. Both the simulation and application results illustrate the effectiveness of the proposed approach. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Representative velocity scale of Rayleigh-Bénard convection with shear-thinning fluids

Although natural convection is frequently encountered in various chemical processes, Rayleigh number (Ra) cannot be defined fully in shear-thinning fluid systems. In particular, the velocity scale, which is necessary to estimate the effective viscosity of the system, should be discussed carefully. Thus, in this study, the representative velocity scale of Rayleigh-Bénard (RB) convection, which is a typical example of natural convection, with shear-thinning fluids was investigated based on the velocity fields obtained using computational fluid dynamics. Numerical simulations revealed that the critical temperature difference at which RB convection starts to fully develop decreases with an increase in the shear-thinning property. The shear-thinning property also induced subcritical bifurcation. In addition, the velocity scale of convection increases with an increase in the shear-thinning property. Thus, the shear-thinning property is considered to accelerate convection. Compared with several types of velocity scales used by other researchers, significant deviations from the actual scale were observed. Therefore, a new type of velocity scale, including the buoyant to viscous force ratio, arbitrary parameter, and thermal diffusivity, was proposed. The proposed velocity scale allowed an approximate estimation of the actual velocity scale. Although further investigation of the validity is necessary with varying geometries and rheological parameters, this velocity scale will be useful for controlling RB convection with Newtonian/shear-thinning fluids.     

One‐Pot/Four‐Step/Palladium‐Catalyzed Synthesis of Indole Derivatives: The Combination of Heterogeneous and Homogeneous Systems

One‐pot, four‐step syntheses of indoles using both solid‐supported heterogeneous and homogeneous palladium catalysts and reagents were carried out. Such a combination of these two‐phase catalysts and reagents causes a dramatic increase in yield, and it is a simple process. The presented methodology is effective for four‐step reactions to provide various functionalized indoles.     

Efficient microbial degradation of bisphenol A in the presence of activated carbon

The biodegradation of bisphenol A (BPA) was carried out with Sphingomonas sp. strain BP-7 and Sphingomonas yanoikuyae BP-11R in the presence of activated carbon (AC). When AC was present, both BPA-degrading bacteria efficiently degraded 300 mg/l BPA without releasing 4-hydroxyacetophenone, the major intermediate produced in BPA degradation, into the medium. The biological regeneration of AC was possible using the BPA-degrading bacteria, suggesting that an efficient system for BPA removal can be constructed by introducing BPA-degrading bacteria into an AC treatment system.     

Numerical Simulation of Sterilization Processes for Shear‐Thinning Food in Taylor‐Couette Flow Systems

The performance of the Taylor‐Couette flow apparatus as a heat sterilizer is numerically investigated. The destruction of Clostridium botulinum and thiamine (vitamin B1) was selected as model reaction. When Taylor vortices were formed in the annular space, the heat transfer significantly enhanced as compared to the case without vortex flow. As a result, the equivalent lethality calculated from the temperature field increased, which is regarded as a quantum leap. Conversely, the improvement of heat transfer induced destruction of thiamine. These results suggest that there is a trade‐off relationship between the enhancement of heat transfer and the avoidance of thermal destruction of nutritional components. In conclusion, the Taylor‐Couette flow sterilizer has the potential for process intensification in heat sterilization processes.     

High resolution extreme ultraviolet spectrometer for an electron beam ion trap

An extreme ultraviolet spectrometer has been developed for spectroscopic studies of highly charged ions with an electron beam ion trap. It has a slit-less configuration with a spherical varied-line-spacing grating that provides a flat focal plane for grazing incidence light. Alternative use of two different gratings enables us to cover the wavelength range 1-25 nm. Test observations with the Tokyo electron beam ion trap demonstrate the high performance of the present spectrometer such as a resolving power of above 1000.     

Application of facial reduction to H ∞ state feedback control problem

One often encounters numerical difficulties in solving linear matrix inequality (LMI) problems obtained from H _∞ control problems. For semidefinite programming (SDP) relaxations for combinatorial problems, it is known that when either an SDP relaxation problem or its dual is not strongly feasible, one may encounter such numerical difficulties. We discuss necessary and sufficient conditions to be not strongly feasible for an LMI problem obtained from H _∞ state feedback control problems and its dual. Moreover, we interpret the conditions in terms of control theory. In this analysis, facial reduction, which was proposed by Borwein and Wolkowicz, plays an important role. We show that the dual of the LMI problem is not strongly feasible if and only if there exist invariant zeros in the closed left-half plane in the system, and present a remedy to remove the numerical difficulty with the null vectors associated with invariant zeros in the closed left-half plane. Numerical results show that the numerical stability is improved by applying it.     

Reduction of H∞ state feedback control problems for the MIMO servo systems

We deal with H_∞ state feedback control problem for the multi‐input‐multi‐output (MIMO) servo system and discuss the advantages of the facial reduction (FR) to the resulting linear matrix inequality (LMI) problems. In fact, as far as our usual setting, the dual of the LMI problem is not strictly feasible because the generalized plant has always stable invariant zeros. Thus FR is available to such LMI problems, and we can reduce and simplify the original LMI problem to a smaller‐size LMI problem. As a result, we observe that the numerical performance of the SDP solvers is improved. Also, as a by‐product, we obtain the best performance index of the reduced LMI problem with a closed‐form expression. This helps the H_∞ performance limitation analysis. Another contribution is to reveal that the resulting LMI problem obtained from H_∞ control problem has a finite optimal value, but no optimal solutions under an additional assumption. This is also confirmed in the numerical experiment of this paper. FR also plays an essential role in this analysis.     

A small three-way valve using particle excitation with piezoelectric transducers for hydraulic actuators

Abstract

Robots composed of hydraulic actuators have been utilized in various fields and at disaster sites. However, the hydraulic control system for multiple-degree-of-freedom mechanisms is large because such systems require many control components. The purpose of this research was to develop a small hydraulic flow control valve. This paper describes the fabrication and evaluation of a small three-way valve by particle excitation using a piezoelectric transducer. This valve consists of two transducers and can switch the inlet and outlet ports by applying an AC voltage of different driving frequencies to each transducer because each transducer has different resonant frequencies. The flow rate was controlled by applying a voltage to the piezoelectric transducer. We evaluated the vibration characteristics of the fabricated three-way valve. The vibration velocity exhibited peaks at 120 and 155 kHz for the inlet and outlet port, respectively, and that of each transducer increased with the applied voltage. Therefore, this three-way valve can switch the opening port by changing the driving frequencies and continuously controlling the flow rate. As a result, we have succeeded in driving the novel small three-way valve.