The bottom of deep sea is one of the fields where robots can work advantageously. This paper introduces a prototype of robot for deep sea survey, which was developed at the University of Tokyo and designated as “PTEROA 150”. The body is designed to decrease the drag force for cruising. To improve controllability for pull-up maneuvering, a pair of horizontal elevators is fitted at the stern. Computer simulation of swimming proves that the longitudinal stability and maneuverability of this robot are suitable for the mission.
An advanced submarine robot model actuated by the driving force in thermo-mechanical transformation of shape memory alloy (SMA) was developed jointly by the engineering faculty of Tohoku University and Honda Seiki Co., Ltd.. A model “robot crab” about 1/20 of practical size was constructed with the artificial muscles of Ni-Ti SMA springs or wires in the every joint parts of the moving legs and it moves by electrical pulse currents with microcomputer controls. It is simple in structure and is also characterized by high strength, high water-pressure and corrosion resistance. It has more rapid motion under water than in air due to the high cooling capacity of water. Based on these characteristics and the advantages of SMA actuator, we have proposed and developed an extreme operation SMA robot model to investigate and collect very deep submarine resources. We also talk about the possibility, some technical problems and necessity for international cooperation in harvesting the deep submarine resources by this type SMA robot in near future.
This article introduces a new interesting method for geometric reasoning in the area of artificial intelligence. This method is called Wu's method, which can automatically prove geometric problems by manipulating algebraic formulae. The reasoning process is similar in a sense to logic which is important as a foundation of symbolic reasoning in artificial intelligence. The Wu's method may provide us a foundation for manipulating spatial geometric information, as logic for symbol manipulation.
The sun emits continuously not only electromagnetic radiations such as X-ray, ultraviolet, visible light, infrared, microwave, radio wave, and magnetic wave, but also a plasma flow consisting of electon and proton plasma, which is called a solar wind. It has recently been recognized that the solar wind is a supersonic flow with a speed of several hundred km per sec emitted from the hot coronal gas surrounding the outermost atmosphere of the sun. The planets of the solar system are immersed in such high speed solar wind plasma, and have a planetary magnetosphere depending on their magnetic moment. The planetary magnetosphere is the outermost magnetic barrier for prevention from the solar wind plasma penetrating into the planetary atmosphere, and is yielded under the electro-magnetic interaction of the planetary magnetic field with the solar wind plasma. The recent studies on the magnetosphere have been devoted to understand our. terrestrial magnetosphere and revealed that the magnetosphere constitutes a system of electrical circuit. Aurora, one of the most beautiful phenomena in our terrestrial magnetosphere, is an electrical discharge of the power generated in the electrical circuit through the solar wind-magnetosphere interaction.
In this report, we present the recent progress in ion beam inertial confinement fusion (ICF). First we review the concept of ICF briefly. Then merits and demerits of ion beam in ICF are discussed. Finally recent researches are introduced.
Ion beams in a periodic magnetic field are investigated theoretically and experimentally. The spatial cyclotron resonance of ion beams is clearly obtained and detailed features of this phenomenon are commented. The resonances for two magnetic field configurations (a multiple magnetic mirror field and a wavy magnetic field) are compared and separation of different ionic species by this phenomenon is discussed.
This report reviews a new scheme for accelerator, the laser beat-wave accelerator. Injection of two intense colinear laser beams into a plasma can produce the coherent longitudinal electric field of the order of 100GeV/m for a plasma density of 1024m-3, if the frequency difference of two lasers equals the plasma frequency. Electrons trapped in the electron plasma wave can be accelerated to high energy. Recent advances made on theoretical, computational, and experimental fronts are described.
A new mechanism of particle trapping and acceleration by waves propagating across a static magnetic field B0 is called the Cross-Field Accelertion (CFA). The principle of CFA is categorized into two types depending on driving waves: the longitudinal electric wave and the transverse electric wave. Some features of particle trapping and acceleration are presented.
Mecahnical alloying (MA) and mechanical grinding (MG) are new methods for the preparation of amorphous alloys using by solid state reaction. The amorphization processes of MA and MG methods are much different each other because of the difference of the starting materials; the former is the mixture of the pure elemental crystalline powders and the latter is the powder of the crystalline compound. However, the amorphous alloys obtained by MA and MG become similar each other in the physical properties and the atomic structure with increasing milling time. On the contrary, the excess defects and strain induced by MA or MG for the amorphization yield the topological and also chemical disorder to the atomic arrangement in comparison with that in the amorphous phase obtained by rapid quenching.
This article reviews the use of the diamond anvil cell for ultrahigh-pressure generation and the Raman and Brillouin spectroscopic methods employed in studying the ultrahigh-pressure properties of materials. In particular, some current studies of the ultrahigh-pressure solid hydrogen are presented; refractive index, equation of state, phase transition, metallization and superconductivity.
Optical absorption and photoluminescence spectra were measured at 77K for transition metal (Mn, Co, Ni) doped In2O3 single crystals grown by flux method. Absorption bands were observed at the photon energy of 2.4 and 1.4eV for Mn doped, 2.5eV for Ni doped and 2.1eV for Co doped In2O3 single crystals at 77K. Oscillator strength of about 10-4 were obtained for the absorption bands of Mn and Co doped In2O3. E1+Vodd type ligand field transition at transition metal was considered for the absorptions as the result of the oscillator strength and the temperature dependence of the absorption bands. Photoluminescence lines were observed at the wavenumber of 17544 and 16529cm-1 for Mn doped, 15267cm-1 for Ni doped and 17544cm-1 for Co doped In2O3 by the excitation corresponding to the photon energy of above absorption peaks. About 0.6nsec of very fast luminescence decay time was observed for Mn and Co doped In2O3 at 77K. Futhermore, several luminescence lines were observed at 77K for higher wavenumber excitation near the indirect transition gap energy of In2O3.
Notion of materials interconnection study is described, and the unusual large width of the study area is stressed. Properties such as electrical, thermal phonon and light conductivities as well as mechanical one are strongly influenced by the presence of interfaces. It is suggested that new frontiers may be opened by the origanization of researchers on this still young study area.
The recent studies on the diffusion and the heat conduction in SiO2 thin films were reviewed. The diffusivities of O2 gas in SiO2 films, which were synthesized the with four different methods, i.e., the thermal oxidation, the chemical vapor deposition, the spin-on glass and the sputtering method, were determined by means of the thermal oxidation of silicon substrates. The results revealed that the difference of the manufacturing methods changes the diffusivities and their activation energies. On the other hand, the spot heating method was developed for measuring the thermal conductivity and the thermal diffusivity of a thin material. The prominent feature is that the geometrial dimensions of a thin sample and the physical properties of a substrate are not required for the analysis. The method could be applied to the material with the thickness of 200μm but should be improved for measuring the thermophysical properties of thin films. The structure of the four kinds of SiO2 films were estimated from the difference of the activation energies of the diffusion of O2 gas.
This paper reviews a calciothermic reduction to produce the several intermetallic compounds. This process can produce the intermetallic compounds directly from the oxide mixtures containig the alloying elements. Metallic calcium, magnesium or calcium hydride can be used for the reducing material because of their strong affinity with oxygen. The general principle of this process is shown in Fig. 1. The methods for the rare-earth permanent magnets such as SmCo5 and Nd-Fe-B, A15-type superconducting compounds such as Nb3Sn and V3Ga, and the refractive compounds such as Ti3Al and TiAl are briefly summarized from the view of the compound powder preparation. The calciothermic reactions can prepare fine, homogenious and clean compound particles in these systems. The phase diagrams of the system among calcium and the alloying elements give the effective informations to produce the stoichiometric compounds.
The X-ray diffraction method was used to measure non-destructively the macrostress and microstress in engineering ceramics [Fig. 1]. For zirconia-alumina composite ceramics, the phase stress in each phase was measured separately, and the macrostress was calculated from the phase stress by using the rule of mixture [Fig. 2]. The compressive residual stress in the surface layer of quenched alumina [Fig. 3] greatly improved the bending strength of the materials [Fig. 4]. The microscopic residual stress, estimated from the broadening of the X-ray diffraction profile, reduced the bending strength of ceramics, when the defect size was small [Fig. 5].
At high fields, standard theoretical treatment leads to formulas, I=Is (1-b/H2-c/H3-…) or μrev=1+Is (2b/H3+3c/H4+…), which are reffered as laws of approach to saturation magnetization. Following Becker and Döring, the coefficient b for cubic crystals was deduced as b=0.0762/Is2[K+1.5(λ100-λ111)σ]2, where σ was applied stress and others were magnetic constants. The values of reversible permeability μrev at biasing field H were measured for steel bars under applied stresses. The results showed that the square root of b was changed linearly with applied stress as theory predicted. The values of magnetic constants K and (λ100-λ111) were determined based on the theoretical formulas; they were affected y chemical composition of materials and heat treatment.
Unusual restriction fragment was detected by DNA blot hybridization with PCNA (DNA polymerase-delta auxiliary protein) probe in a case of congenital malformation. Chromosomal in situ hybridization indicated the location of PCNA gene to the region of human chromosome 2q31-35. To discover the locus more closely associated with congenital malformation, a cloned DNA segment which has been mapped to chromosomal region 2q33-36 was tested for restriction fragment length polymorphisms (RFLPs). The 2q33-36 probe showed 2.1Kb, 1.9Kb and 1.7Kb fragments in five normal control samples. In seven cases of congenital malformations examined, however, the band of 2.1Kb was absent in six cases and the band of 1.7Kb in one case. The causes of these congenital malformations have not been explained clearly yet. These results indicate the relationship between congenital malformations and proximity of PCNA locus.