Viewer,converter and preprocessor for smart machining process using an industrial robot

In this paper, viewer and converter softwares are presented for smart machining process using an industrial robot. The viewers for NC, CLS, DXF and STL files illustrate their surface representation with normal direction vectors. For example, the DXF is a data format developed by Autodesk to realize data interoperability among different makers’ CAD systems. The STL means Stereolithography which is a file format proposed by 3D Systems and recently is supported by many design tools and CAD/CAM softwares. In addition, the converters for DXF and STL files generate the corresponding CLS files with normal direction vectors for machining. Further, the proposed preprocessor allows the developed machining robot to work based on information included in STL files. The convenience and user-friendliness of the proposed integrated system are confirmed through experiments of viewing, converting and machining.     

Coking reaction in hydrogenation

Asphaltene prepared from a Japanese coal (Akabira, 81.2 wt% C) and coal tar pitch were heat treated under nitrogen or hydrogen. Under nitrogen the initial thermal decomposition produced radicals which abstracted hydrogen from other molecules to stabilize and to produce smaller molecules and gas. The molecules from which hydrogen was abstracted as well as other radicals polycondensed to produce heavier solvent-insoluble fractions. Under hydrogen the radicals were stabilized by hydrogen gas to produce smaller molecules avoiding the production of a heavier fraction. The higher the hydrogen pressure, the smaller was the yield of heavier fraction and the larger the yield of lighter fraction. Higher temperature accelerated the production of the heavier fraction. Donor solvents could reduce the production of the heavier fraction.     

Theoretical conformational analysis of tetrapeptide Ac-Cys-Pro-Gly-Cys-NHMe with disulfide linkage

Theoretical conformational analysis was carried out for the acyclic and cyclic tetrapeptides Ac-Cys-Pro-Gly-Cys-NHMe using ECEPP and optimization procedure for investigating the conformational preference of peptides having disulfide linkage. Calculated results indicate that cyclic Ac-Cys-Pro-Gly-Cys-NHMe forms compactly fold conformations with type II β-bend at the Pro-Gly portion, and also show fairly good agreement with experimental results of the NMR spectroscopy for the tetrapeptides having Cys-Pro-Gly-Cys sequence. Received: 26 August 1996/Revised version: 18 September 1996/Accepted: 23 September 1996     

Pressure and temperature effects on the hydrogenation of coal-derived asphaltene

Pressure and temperature effects on hydrogenation reactions were examined using coal-derived asphaltene at 390,420 and 450 °C, under 3 and 10 MPa of hydrogen partial pressure. Higher conversion was obtained at higher reaction temperatures. Benzene-insoluble material (Bl) was formed at higher temperatures especially at low hydrogen pressure, this Bl being one-third of the reaction product at 450 °C. From structural analysis of unreacted asphaltenes and product oils, at 390 °C, it was concluded that smaller molecular components convert to oil initially and the larger molecules remain as unreacted asphaltene. Under higher hydrogen pressure for all temperatures carbon aromaticity (f_a) and number of aromatic ring per structural unit (R_aus) in unreacted asphaltenes were lower than those under lower hydrogen pressure suggesting that hydrogenation of the aromatic nucleus was promoted by higher pressure. At lower hydrogen pressure, R_aus for asphaltenes at higher temperature is larger than that at lower temperature. This suggests that at lower hydrogen pressure, dehydrogenation or condensation reactions occur more easily. A large effect at higher hydrogen pressure was a reduction in the extent of condensation reactions. Higher reaction temperatures contribute to splitting of bridged linkages so reducing molecular size and degree of aromatization.     

Theoretical conformational analysis of tetrapeptide Ac-Cys-Pro-D-Ala-Cys-NHMe with Disulfide Linkage

Summary. Theoretical conformational analysis was carried out for the acyclic and cyclic tetrapeptides Ac-Cys-Pro-d-Ala-Cys-NHMe using ECEPP and optimization procedure for investigating the conformational preference of peptides having disulfide linkage. Calculated results indicate that cyclic Ac-Cys-Pro-d-Ala-Cys-NHMe forms compactly fold conformations with type II β-bend at the Pro-d-Ala protion, and also show fairly good agreement with experimental results of the NMR spectroscopy for the tetrapeptides having Cys-Pro-d-Ala-Cys sequence. Received: 23 March 1997/Revised: 25 June 1997/Accepted: 4 July 1997     

Solid conversion behaviors of indium oxide gel consisting of hybrid clusters with thermal- and/or ultraviolet-treatments for low temperature processing

Herein, the thermal and ultraviolet (UV)-irradiation solidification of indium-oxide (In-O) cluster gel, which is made from an indium acetylacetonate solution using propionic acid as a solvent, is reported. The cluster gel is an assembly of hybrid clusters, which has In-O cores coordinated with organic ligand molecules. It is confirmed that the well-defined structure of the cluster gel enables us to have a predictable solidification in the thermal treatment. Hence, we are able to understand what happens in each temperature stage from solution to solid, which can be strictly defined. It is observed that even the amount of the residual solvent in the gel is a function of temperature. The limitation of thermal pyrolysis is also clarified in the carbon-based solution. Some amounts of hybrid clusters remain even after annealing at 500 °C, leading to a carbon content that is higher than 10 at% and large Vth shift due to many defects in the fabricated thin-film transistors. As for the UV treatment, it is confirmed that the UV irradiation solidifies the gel even at room temperature (RT). Moreover, it is found that the UV reactions generate new carbon bonds, which have a higher binding energy than those in the starting gel. Although the residual organics in the gel prevent the growth of the In-O core in the case of UV irradiation at RT, the combination of thermal and UV treatments makes possible the growth of fine In-O crystals with reduced (2 at%) and stabilized carbon elements. As a result, it can be stated that a good semiconductor film is developed even at a temperature as low as 200 °C by using this combined treatment.     

Incident energy dependence of the scattering dynamics of water molecules on silicon and graphite surfaces: the effect on tangential momentum accommodation

The scattering dynamics of water molecules on solid surfaces was investigated using the molecular beam technique. In contrast to the experiments previously reported in the literature, the range of incident energy was chosen to cover the typical kinetic energies of gas molecules in equilibrium at room temperature (35–130 meV). Even in such a narrow energy range, the angular distribution of scattered molecules is heavily affected by the incident energy, exhibiting both a nearly cosine distribution and a lobular distribution, which has a clear peak close to the specular direction. Interestingly, the tangential momentum accommodation coefficients (TMACs) estimated from the scattering experiments show opposite energy dependences on graphite (0001) and silicon (100) surfaces. As the incident energy increases, the TMAC decreases on the graphite surface, whereas it increases on the silicon surface. These trends can be attributed to the relatively large adsorption energy of water molecules on these surfaces and the atomic-scale surface corrugation, although a rigorous understanding requires further analysis by molecular dynamics simulations. Our findings suggest the need for an elaborate slip-flow model that takes account of the incident energy effect to accurately analyze water vapor flow in micro/nanostructures, which is ubiquitous in nature and engineering applications.     

High-speed stability of a rigid rotor supported by aerostatic journal bearings with compound restrictors

Demands for higher rotational speed and accuracy for effective manufacture of small holes on printed circuit boards and very small precise parts have been increasing remarkably. Aerostatic journal bearings with compound restrictors have greater stiffness than those with conventional inherently compensated restrictors and are one of the most effective candidates to satisfy these demands. In this work, the instability of a rigid rotor supported by aerostatic journal bearings with compound restrictors was investigated numerically and experimentally. It was found that this type of aerostatic bearings showed a much higher threshold speed for instability compared with bearings with inherently compensated restrictors.