数控机床的防碰撞系统

当今世界的制造业正面临着高附加价值加工的转换,复合加工机、5轴联动机床、5面体加工中心等最新加工设备层出不穷。但是在加工车间,随着这些以复合加工机为代表的机械结构的复杂化,机械运动和机械操作也越来越复杂。在机加工操作中,刀具和工件以及夹具的干涉、机床单元的干涉比以前更加易于发生,需要操作工小心和熟练地操作。因此,迫切需求让机床操作工安全操作的机床。     

Anionic polymerization of methyl methacrylate in the presence of chromium carbonyl [Cr(CO)6]

Summary The presence of Cr(CO)₆ in nBuLi-initiated anionic polymerization of methyl methacrylates (MMA) was found to effectively enhance stereoselectivity of the polymerization in toluene at 0°C. nBuLi/Cr(CO)₆ afforded an isotactic PMMA with 86 % of mm triad, and the polymers obtained with nBuLi/Cr(CO)₆/tBuOK were rich in heterotactic structures (mr = ca. 54%). In both cases, the selectivity was improved in ca. 10% compared to those of the polymerization conducted under the similar conditions without Cr(CO)₆. Received: 20 January 2003/Revised version: 21 April 2003/Accepted: 21 April 2003 Correspondence to Eiji Ihara     

Optical soliton transmission experiment in a comb-like dispersion profiled fiber loop

We discuss the properties of comb-like dispersion profiled fiber (CDPF) for an optical soliton transmission. It is found that the CDPF in which the standard single-mode fiber is placed both at the first and at the end of each section is more suitable to reduce dispersive waves if chirp-free transform limited optical pulse is used as a light source. A 10-ps optical soliton transmission experiment is performed in such a CDPF over 1000 km with the amplifier spacing of 80 km that corresponds to 3.1 times the dispersion distance.     

Photoaffinity labeling of peroxisome proliferator binding proteins in rat hepatocytes; dehydroepiandrosterone sulfate- and bezafibrate-binding proteins

Neuronal nitric oxide synthase produces nitric oxide, a radical involved in neurotransmission as well as in cytotoxicity during stroke and neurodegenerative diseases. In the adult Wistar rat neuronal nitric oxide synthase-positive neurons are inhomogenously distributed along defined cortical areas, with highest densities (18 cells/mm2) in cingular area 1, piriform cortex, frontal motor area Fr 2 and in the medial visual association area Oc 2MM. A medium packing density of neuronal nitric oxide synthase neurons (10/mm2) characterizes primary sensory areas, whereas retrosplenial cortices contain lowest cell numbers (3-5/mm2). The data suggest that functions of certain cortical areas are more dependent on intracortically produced nitric oxide than others, and that cortical injury may cause more severe nitric oxide related cytotoxicity in areas with higher numbers of neuronal nitric oxide synthase-positive neurons.     

Microstructural analysis of NiInGe ohmic contacts for n-type GaAs

NiInGe ohmic contact materials, which are attractive to use in future GaAs devices, were previously developed in our laboratories. Although the NiInGe contacts provided low contact resistances of about 0.3 Ω-mm and excellent thermal stability, further reduction of the contact resistance (R_C) of the NiInGe contacts was mandatory to use these contacts in submicron devices. In this paper, the microstructural parameters, which influence the R_C values, were investigated by correlating the R_C values with the microstructure at the interface between the contact materials and the GaAs substrate. The R_C values of the NiInGe contacts were found to depend strongly on the volume fraction and the In concentration (x) of the In_xGa_1−xAs compound semiconductor layers, which were formed at the metal/GaAs interface. Both the volume fraction and the In concentration of the In_xGa_1−xAs layers were found to depend on the thickness of the In layer used in the NiInGe contact and the annealing temperature to form the ohmic contact. A R_C value of 0.18 Ω-mm was obtained for the Ni (18 nm)/In (13 nm)/Ge (30 nm) contact (where a slash “/” indicates the deposition sequence) after annealing at temperature of 650°C for 5 sec.     

Entropies of general quantum states

The entropy and the mutual entropy for states and channels are totally studied in general quantum systems described byC*-algebras. In particular, we discuss the relations among theS-entropy and the mutual entropy introduced by Ohya and the Connes-Narnhofer-Thirring entropy.     

Hydrothermal Synthesis and Low-Temperature Sintering of Zinc Gallate Spinel Fine Particles

Nanosized powders of single-phase zinc gallate (ZnGa₂O₄) spinel were hydrothermally synthesized from solutions in the presence of NaOH over the pH range of 1.9 to 7.0 and from solutions above pH 7.0, i.e., the very basic medium (pH of 13.85), by removing the residual ZnO phase by washing with aqueous H₂SO₄ from the precipitate mixtures of zinc gallate spinel particles and ZnO. A very wide compositional range (Zn/2Ga = 0.705–1.157) of zinc gallate spinel solid solutions could be hydrothermally synthesized in the form of nanosized particles from acid and very basic mediums (pH of 2.4–13.85) in the presence of NaOH. These hydrothermally synthesized spinel powders showed good sinterability and almost full densification at 1100°C for 1 h. Dense sintered bodies consisting of single-phase zinc gallate spinel were fabricated at 1100°C using zinc gallate spinel powders having almost stoichiometric composition formed from the solution at pH 9.95 in the presence of aqueous ammonia.     

Improvement of inverse heat conduction solution using Laplace transformation: Method of partial division of time

Any solution for an inverse heat conduction problem makes the estimation of surface temperature and surface heat flux worsen in the case where these values behave like a triangular shape change with time. In order to compensate for this defect, Monde and colleagues, who succeeded in obtaining analytical inverse solutions using the Laplace transform technique, introduce a new idea where these changes over the entire measurement time can be split into several parts depending on the behavior. Therefore, an approximate equation to trace the measured temperature change can be derived, resulting in good estimation of surface temperature and surface heat flux even in the case of the triangular shape change and sharp change. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(7): 630–638, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10117     

Effects of electrolyte on the structure of pyrolytic graphite surfaces in anodic oxidation

Anodic oxidation effects on the structure of the basal and edge surfaces of pyrolytic graphite in alkaline electrolytes have been studied. Laser Raman spectroscopy, a gas-phase chemical modification method, coupled with X-ray photoelectron spectroscopy and secondary ion-mass spectroscopy techniques, were used. Anodic oxidation of the surfaces of pyrolytic graphite in alkaline electrolytes does not cause destruction of their surface structure, even at a higher level of treatment, unlike oxidation of acid electrolytes. In alkaline electrolytes, the number of hydroxyl groups added on the edge surface gradually increases with the increase in treatment level, whereas the number of carboxyl groups does not increase. It was found that anodic oxidation in alkaline electrolytes has a wider permitted range of treatment, in which hydroxyl groups can be added without destroying the edge surface structure, than that found in acid electrolytes. On the other hand, the number of hydroxyl groups added by treating with alkaline electrolytes is smaller than that with acid electrolytes. At a higher treatment level with acid electrolytes, oxidation occurs, even to a depth of 40 nm from the edge surface, whereas with alkaline electrolytes, oxidation occurs only at the surface. On the basis of these results, the effects of electrolytes on the adhesion between carbon fibres and epoxy resin matrix are discussed.