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We have accomplished the ruthenium-catalyzed benzylic substitution of benzyl esters with a stabilized carbon nucleophile. A [Cp*RuCl2]2/picolinic acid catalyst system promoted the reaction of 2-naphthylmethyl-2,3,4,5,6-pentafluorobenzoates with a series of stabilized carbon nucleophiles such as malonates, β-ketoesters, and diketones to give the corresponding benzylic alkylation products in moderate to high yields. We proposed a plausible reaction mechanism that could involve a (π-benzyl)ruthenium intermediate.

Drilling into carbon fiber-reinforced plastics (CFRP) with conventional tools often results in defects like delamination, fiber pull-out, etc. In order to achieve high-quality CFRP hole machining, we developed a new woven metal wire tool (WMW tool) based on core drilling, with electrodeposited diamond grains. Using this tool, we conducted 20-mm diameter core drilling on a CFRP plate with grinding fluid supplied from the inner side of the WMW tool at the grinding point. The new tool also removes chips easily. The method produced high-quality holes without delamination or burr at the entry or exit at a practical feed rate of 100 and 300 mm/min. Although wear was observed on the tip of the wire mesh, new diamond grains appeared at the tip, so that the tool exhibited a self-sharpening effect. The newly developed MWM tool achieved a drastic reduction of chips and superior machined surface at the same time in CFRP drilling.

We have succeeded in solution growth of SiC from Cr solvent without Si using ceramic SiC as the SiC source. The effect of the growth conditions, such as the liquid height in the crucible, on the crystal quality in solution growth of SiC from Cr solvent was investigated. For a liquid height in the crucible of up to 10 mm, the growth rate increases with increasing liquid height and the SiC crystals are a single polytype, while the growth rate decreases and the crystals are polycrystalline for a liquid height above 10 mm. In the former case, the balance between dissolution and transportation of the solute are comparable. The latter case is expected to be transportation limited because transportation of free C and Si atoms is inhibited by excrescent crystals in solution and the increase in the distance for solute transportation. In addition, a higher growth temperature leads to growth of only 4H-SiC.

SiC crystals are grown using a Si-Cr-based solvent by a top-seeded solution growth (TSSG) method by changing the dipping time after when the growth temperature is reached. Step-flow-like curve morphologies were observed for a dipping time after 15 min, while polycrystallization occurred at the periphery for that after 120 min, which corresponded to the dipping under unsaturated and supersaturated carbon in the solvent, respectively. Furthermore, the solution growth of SiC with dipping under unsaturated carbon was easily realized by the growth from the crucible bottom, step-flow-like growth was achieved. Using this technique, dominant polytypes of SiC in various growth conditions after stable seed dipping under the unsaturation in the solvent can be demonstrated.

Si0.56Cr0.4M0.04(M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Rh, and Pd) solvents were investigated to identify new multi-component materials in which carbon is highly soluble, because solubility is a key parameter in solution growth of SiC. The solubility of carbon in Si0.56Cr0.4Co0.04was 8.37 at%, the highest value among the tested multi-component materials. This is about 2.5 times the solubility of carbon in Si0.6Cr0.4. These results show that addition of a small amount of a transition metal enhanced the solubility of carbon in Si0.6Cr0.4. This technique for determining carbon solubility is effective for investigating crystal growth using solvents with several components, for which complex thermodynamic calculations are necessary.

The kinetics of vapor phase dephosphorization from tri-calcium phosphate (TCP) by carbothermic reduction was studied with and without the presence of Fe3O4. Microwave heating was utilized to obtain large variations in the heating rate (HR). In the reduction of TCP alone, the phosphorous removal fraction (RF; equal to ∆P2O5/P2O 5 0 , where ∆P2O5 is the weight change and P2O 5 0 is the P2O5 weight before heating) decreased as the HR increased. In other words, a shorter residence time at a high temperature resulted in a smaller reduction fraction of TCP. An apparently third-order reaction was postulated to account for the kinetics using a fitting simulation based on the additive law of the reaction progress. On the other hand, the phosphorous removal (dephosphorization) rate (RR; equal to ∆P2O3/tMW, where tMW is the microwave heating time period) increased as the HR increased above 1200 °C. The reduction ratio of Fe3O4 above 1100 °C is higher than 97 pct regardless of the heating rate. The reduction of TCP in the presence of Fe3O4 showed that RF increased slightly with increasing HR despite a shorter residence time at a high temperature. The RR also increased with the HR even though RF decreased to half of the values observed in the cases without Fe3O4 for temperatures above 1200 °C. The practicality and optimal operation conditions of phosphorus vapor removal were discussed.

Evaporation of the volatile solute from the liquid phase is a common problem for the crystal grown from solution, especially for the growth under high temperature. In the present study, a numerical model was constructed to quantitatively investigate the evaporation process in crystal growth. This model was applied in top-seeded solution growth (TSSG) of SiC crystal to simulate the transport of aluminum (Al), which is important for crystal surface morphology but easy to vaporize. The transport path of Al in the growth system was determined by analyzing the possible reactions on different boundaries. Accordingly, an improved structure was proposed to suppress the evaporation loss of Al during long-term growth, and was compared with the original case both numerically and experimentally. The simulation results showed that the improved structure could effectively decrease the Al loss by over 70%, and meanwhile had almost no influence on the thermal and flow environment in the solution. For the experimental results, the improved case presented much lower spontaneous nucleation possibilities and higher step height on the crystal surface, which matched well with the features of high Al addition in literatures. Therefore, the improved structure proposed in the present study was proven to be effective to enhance the composition stability of solution during long-term SiC solution growth, and this numerical method could be applied in the growth of other crystals facing the similar problem.

For solution growth of silicon carbide, it is significant to understanding the evolutionary mechanism of step bunching. This study infers that solute’s incorporation into steps and transport together determines step bunching progress. The occurrence of step bunching is due to the depletion of solute in the region with high step density, caused by a high step kinetic coefficient. On the other hand, by promoting the transport of the solute in the solution, the step speed becomes uniform, thereby the step bunching can be prevented. Furthermore, we proposed a non-dimensional Damkohler number for crystal growth in step-flow mode. It correlates incorporation rates with bulk diffusion rates and can build a phase map of growth rates and step bunching stability. Several solvents are located in the phase map, demonstrating the possible usage of the phase map as a pointer for solvent designing.

The transition metal-catalyzed stereospecific benzylic alkylation of optically active benzyl esters with active methylene compounds remains extremely rare. Herein, we describe the study for the ruthenium-catalyzed benzylic alkylation of chiral benzyl esters with malonates as a carbon nucleophile. A combination of [Cp*RuCl2]2 and picolinic acid found to be effective for the title reaction, providing the chiral benzylic alkylation products with retention of stereochemistry of the starting material. We proposed that the ruthenium catalysis would proceed via a double inversion mechanism.

This work assessed the effects of adding Al to a molten Cr solvent on the surface morphology of the SiC crystals resulting from solution growth without molten Si. Al was added to a pure Cr solvent at compositions of 0, 4 or 20 mol%, and the heights of macrosteps for the solvents with any composition of Al were at most one fifth of those obtained without Al. The frequency of two-dimensional nucleation was examined, based on calculating the surface energy of each solvent from viscosity values. The viscosity of the pure Cr solvent was found to decrease with increasing Al addition, such that the surface energy was also lowered. This phenomenon in turn lowered the two-dimensional nucleation frequency, such that surface roughening is considered to be reduced. The addition of Al to the Cr solvent is evidently beneficial in terms of growing smoother crystals.

科研費報告書収録論文(課題番号:07455416・基盤研究(B)(2)・H7～H9/研究代表者:内山, 勝/フレキシブル双腕ロボットの協調制御に関する研究), Proceedings : 1997 IEEE International Conference on Robotics and Automation : April 20-25, 1997 Albuquerque, New Mexico

Cytophaga sp. strain L43-1 secretes a collagenase [Y. Sasagawa et al., Biosci. Biotech. Biochem., 57, 1894-1898 (1993)]. A cog gene encoding the collagenase from this strain was cloned, and the nucleotides were sequenced. The structural gene of cog consisted of 3846 base pairs, which encoded a polypeptide consisting of 1282 amino acid residues with a predicted molecular mass of 130 kDa which was synthesized as a pre-matured enzyme. The deduced N-terminal 14 amino acids sequence, molecular mass of 120 kDa, and pI of 4.96 of the predicted matured enzyme were consistent with those previously found for the collagenase purified from the strain. The cog gene was expressed in Escherichia coli using the lac promoter and ribosomal binding sequence in plasmid vector pUC119 or pKK223-3, but not its own putative promoter and Shine-Dalgarno sequence. The consensus amino acid sequence (His-Glu-Xaa-Xaa-His) of an active site of the metal proteases including the collagenase from Vibrio arginolyticus and a series of human MMPs was found in the Cog protein of the strain.

This paper proposes the estimation algorithm of some positional relationships between two robots and a car for a car transportation system. The car transportation system in this paper consists of two mobile robots and they lift drive wheels of the car to move the car. The knowledge of positional relationships between two robots and the condition of nonholonomic constraints of the car are necessary to transport the car. However, it is difficult that the parameters of positional relationships are obtained by using laser range scanners, cameras and GPS in the system. In the proposed algorithm, the encoders and the force sensors on the robots are used. To estimate the positional relationships, two robots lifting a car are moved by the cooperative transportation control based on force control. And then the information of two robots' velocities which are obtained by odometry is collected. After that, the relative position and orientation between two robots, the relative orientation between each robot and a car and the wheelbase of the car are together estimated by using the information and the extended Kalman filter. In this paper, the procedure of the estimation algorithm of some positional relationships between two robots and a car and the primary experiments confirming the estimation capability of the proposed algorithm are described.

This paper proposes a new cooperative transportation control algorithm in consideration of not only the internal force but the external force applied to “Mobile Robot for a Wheel (MRWheel)”. First, we describe the merits and demerits of the model-based external force compensation method proposed in our previous study and explain the necessity of this new control algorithm. Secondly, we explain this new control algorithm mathematically. In this new algorithm, each follower receives the motion errors estimated by the other followers with TCP/IP, which enables each follower to estimate its motion error by using the force applied to it. Moreover, this new algorithm also enables “intelligent Cooperative Autonomous Robot Transporters-type II (iCART II)” to transport many types of cars at a variety of places without the preliminary car transportation needed for identifying the model parameters of the external force. Finally, we conduct the transportation experiments of two types of cars for the comparison between this new algorithm and the conventional algorithm with the modelbased external force compensation method. These experimental results illustrate the validity of this new control algorithm.

This article describes the concept of a novel car transportation system including two mobile robots with a lift mechanism for single wheel. The system lifts only two drive wheels of a front-wheel-drive vehicle or a rear-wheel-drive vehicle, and transports them. However, the system has nonholonomic constraints because all wheels of a vehicle are not lifted by the system. This article also describes a motion control method and a vehicle's wheelbase estimate algorithm for the proposed system in order to maneuver the vehicle. The motion control method is based on control theory for a three-wheeled cycle system. On the other hand, the vehicle's wheelbase estimate algorithm includes impedance control, and the system estimates the vehicle's wheelbase from constraint forces during transporting the vehicle. Finally, two experiments show that the proposed system can maneuver the vehicle.

In this paper, a new car transportation system and a prototype robot that are based on the “a-robot-for-a-wheel” concept are introduced. In addition, a decentralized control algorithm for cooperative car transportation using a leader–follower type of multiple robot system is proposed. An external force compensation method is explained for extracting only internal force from the force applied to the robots. The proposed algorithm is experimentally validated by application to a car transportation system. Finally, the application of the proposed system to medical and welfare mobile apparatuses is described.

The car transportation system, which termed as iCART (intelligent Cooperative Autonomous Robot Transporters), is developed for handling the car in the narrow space, substituting the parking and unmanning the transportation of cars. iCART is composed of two robots and these robots transport the car in coordination based on a leader-follower type distributed motion control algorithm. To avoid damaging the surface of the car, tires of the car are putted on, not grasped by, the end-effecter of robots. Thus, when force/moment applied to the car by robots becomes large, the slip at the contact of the robot with the car occurs. Due to the slip, the relative position between robots is changed. In a conventional algorithm, the relative position is used for the control. Thus, after the contact of the robot with the car slips, occasionally, robots could not coordinate. For overcoming this problem, the motion control algorithm based on the caster-like motion is applied to the car transportation system iCART in this paper. Since this algorithm does not use the relative position information, the system becomes robust against the slip at the contact of the robot with the car. The proposed motion control algorithm is applied to iCART and experimental result illustrates the validity of the proposed algorithm.

In this paper, we propose a new car transportation system referred to as iCART(intelligent cooperative autonomous robot transporters). This system consists of two robots for the car transportation. Each robot is controlled by using a decentralized control algorithm for transporting the car in coordination. A trajectory for transporting the car is given to one of robots, and another robot estimates the trajectory through the interaction force between two robots. This car transportation system could transport any size of cars, and is available for any kinds of car transportation tasks such as parking, ballet parking, tow away service, and the transportation of cars at a factory, ferry, parking area, etc. The proposed car transportation system are developed and the control algorithm is experimentally applied to them. The experimental results illustrate the validity of the proposed system.

One of the most amazing phenomena widely observed in nature is self-assembly; living systems spontaneously form their body structure through the developmental process. While this remarkable phenomenon are not thoroughly understood in biology, the concept of self-assembly becomes undeniably indispensable also in artificial systems as they increase in size and complexity. Based on this consideration, this paper discusses the realization of self-assembly with the use of a multi-robotic system each of which has simple motile function. The main contributions of this paper are twofold: the first concerns a fully decentralized control method derived from the mutual entrainment between coupled nonlinear oscillators; and the second is related to the exploitation of inter-modular physical interaction stemming from a passive deformation mechanism, which allows an efficient movement of individual modules during the course of self-assembly. Here, form generation by self-assembly is considered as the result of time evolution toward the most dynamically stable state. Owing to this, in principle, the proposed method also satisfies significant ability of self-repair without making any modification to the proposed algorithm. Simulation results show that stable and spontaneous self-assembly is achieved irrespective of the initial positional relationship between the modules.

科研費報告書収録論文(課題番号:07455416・基盤研究(B)(2)・H7～H9/研究代表者:内山, 勝/フレキシブル双腕ロボットの協調制御に関する研究), IROS 96 : proceedings of the 1996 IEEE/RSJ International Conference on Intelligent Robots and Systems : robotic intelligence interacting with dynamic worlds, November 4-8, 1996, Senri Life Science Center, Osaka, Japan

科研費報告書収録論文(課題番号:07455416・基盤研究(B)(2)・H7～H9/研究代表者:内山, 勝/フレキシブル双腕ロボットの協調制御に関する研究), Proceedings : 1996 IEEE International Conference on Robotics and Automation : April 22-28, 1996 Minneapolis, Minnesota

Fluorescent granular perithelial (FGP) cells introduced by Mato et al. (1979, 1980, 1981) are situated in the Virchow-Robin space of cerebral microvessels and exhibit a marked uptake capacity for the endo- and exogenous materials in physiological conditions. That is, the FGP cells are the perivascular macrophage lineage enclosed by a basal lamina and glia limitans and are distributed between blood vessels and cerebral parenchyma. As reported previously, the FGP cells were distinguishable from microglia and pericytes in their morphology, location, and epitopes on their cytoplasmic membrane. On the other hand, it is established that microglia are upregulated by lipopolysaccaride (LPS) administration, but it remains unsettled whether the FGP cells, the perivascular macrophagic cells, are activated by LPS or not and what role the FGP cells play in the upregulation of microglia. Thus far, the morphological relationship between FGP cells and microglia in the process of upregulation has not been clarified. Thirty-six 7-month-old Wistar male rats were employed. The animals were sacrificed at 2, 5, 10, 24, and 72 h after the intravenous administration of 500 microg/kg of LPS. The FGP cells and microglia in their cerebral cortex were studied with immunohistochemical and electron microscopical techniques. The findings of the present study indicated that the majority of FGP cells were upregulated by LPS from the results of immunohistochemical and morphological data, but some of them tended to degenerate. Furthermore, in the time course after LPS administration, microglia were also upregulated and approached the microvessels and occasionally contacted the FGP cells directly. From these findings, it is hypothesized that FGP cells may significantly influence the mobilization and upregulation of microglia caused by LPS administration.