Robot simulator in TIPS/Geometric Simulator

With the growth of factory automation, the need for off-line robot programming is increasing rapidly. Off-line programming requires a robot simulator. This is the reason for the development of a TIPS/GS (Geometric Simulator), accompanied by a robot simulator. TIPS/GS has been developed as a project in the TIPS Research Association. The goal of this project is to extend the functions and applications of the solid modeler TIPS-1. Four simulators (i.e. the assembly simulator, engineering, NC simulator and robot simulator) have been developed for these extended applications.

The robot simulator described in this paper has the following special features:

• • When a robot motion is prescribed by the VAL-G language, the result can be seen on a CRT display in several patterns.

• • High-speed dynamic display which can almost keep up with real-time movements.

• • A shaded as well as wire-frame picture is used for the high-speed display entioned above.

• • Supported by the solid modeler, any robot and environment can be used with this system.

• • The preparation of a precise interference checker based on an analytical methods.

This paper is a report on the development of the robot simulator.     

Effect of basicity of metal doped ZrO2 supports on hydrogen production reactions

The basicity of ZrO₂ support was successfully controlled by doping La and alkaline earth metals. La doping significantly increased weak basic sites, and medium and strong basic sites appeared by the further increase of La doping. Mg and Ca doping on La doped ZrO₂ increased weak and medium basic sites, respectively. Significant increase of total number of basic sites including strong basic sites was observed by Sr doping. In ammonia decomposition, turn over frequency (TOF) of ammonia over Ru supported ZrO₂ and metal doped ZrO₂ exhibited a good relation to the number of medium and strong basic sites. From TOF with different reaction temperature, it was supposed that the higher basicity is effective to recombinative desorption of nitrogen at lower reaction temperatures, whereas the number of medium basic sites would be effective at a high reaction temperature. Catalytic activity in dry reforming of methane was evaluated over Ru supported ZrO₂ and metal doped ZrO₂ as well. The catalytic activity was improved by metal doping to the supports. Both TOF of CO₂ and methane showed a good relation to the total number of basic sites as well as the number of medium and strong basic sites. It was interestingly found that H₂/CO was increased with an increase in the total number of basic sites. This implies the weak basic sites would have a positive impact on H₂/CO.     

Radiation-induced amorphization resistance and radiation tolerance in structurally related oxides

Ceramics destined for use in hostile environments such as nuclear reactors or waste immobilization must be highly durable and especially resistant to radiation damage effects. In particular, they must not be prone to amorphization or swelling. Few ceramics meet these criteria and much work has been devoted in recent years to identifying radiation-tolerant ceramics and the characteristics that promote radiation tolerance. Here, we examine trends in radiation damage behaviour for families of compounds related by crystal structure. Specifically, we consider oxides with structures related to the fluorite crystal structure. We demonstrate that improved amorphization resistance characteristics are to be found in compounds that have a natural tendency to accommodate lattice disorder.     

Quasi‐static and chaotic characteristics of the natural convection field between concentric vertical annuli

In this study unsteady and chaotic characteristics of thermal convection fields between concentric annuli were experimentally examined, and they were compared with those reported in a vertical slot. The inner cylinder was heated by an embedded heater and the outer one was cooled by temperature‐controlled cold water, and 84 wt% glycerol‐water solution was used for the present test liquid. The main results are as follows: (1) The region where the characteristic frequency of temperature fluctuation is detected is located in the upper portion of the region where the secondary cells exist. (2) The time scale of the temperature change at which the autocorrelation coefficient becomes 1/e is relatively small in the secondary‐cell region, and this corresponds to the result of the natural convection field in a vertical slot. (3) The significant chaotic characteristics of temperature fluctuation are observed in almost the same region where the characteristic frequency of temperature fluctuation is detected, and this also corresponds to the results on the vertical slot. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(6): 486–497, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10048     

Metal Vapor Behavior in GTA Welding of a Stainless Steel Considering the Marangoni Effect

A gas tungsten arc in helium was modeled taking into account the contamination of the plasma by metal vapor from the weld pool. The whole region of gas tungsten arc atmosphere including the tungsten cathode, arc plasma and weld pool was treated using a unified numerical model. The anode was of a low sulfur stainless steel or a high sulfur stainless steel. A viscosity approximation was used to express the diffusion coefficient in terms of viscosity of shielding gas and metal vapor. The transient two-dimensional distributions of the temperature, velocity of plasma flow and iron vapor concentration were predicted, together with the weld penetration at the atmospheric pressure. The distribution of the iron vapor is obviously different between the case of a low sulfur stainless steel anode and the case of a high sulfur stainless steel anode. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Effectiveness of downward evacuation in a large-scale subway fire using Fire Dynamics Simulator

Effective evacuation routes in the case of a large-scale subway fire were studied. A serious problem in the subway fire is that the directions of smoke flow are coincident with those of evacuation toward the surface. Hence, it is necessary to design an evacuation route without interference from smoke. A disastrous fire broke out in the Jungangno subway station in Daegu, South Korea in 2003. Based on this case, the Jungangno subway station with three basement levels was used in Fire Dynamics Simulator model in this study. The influences of smoke, temperature, and toxic gases (carbon monoxide [CO] and carbon dioxide [CO₂]) were computed at the evacuation staircases in the subway station with a fire source in the third basement floor (B3). The calculations showed that the evacuation staircases had high smoke density, temperature, and concentrations of CO and CO₂ in the subway fire. Hence, these factors greatly affected all of the upward evacuation staircases due to the coincidence of the smoke flow and the evacuation routes. Therefore, our paper proposes a new subway station with a fourth basement floor (B4) having downward evacuation routes which are in the opposite direction to the smoke flow. The results of analysis show that these factors hardly affected the staircases from B3 to B4. We conclude that downward evacuation can be more effective than upward evacuation for a large-scale subway fire.     

稻田花岗岩中的流体包裹体及由其导致高温条件下微小裂纹的形成

几乎在所有花岗岩的石英及长石中都含有很多流体包裹体。通过常温及高温显微镜观察，查明了稻田花岗岩中流体包裹体的初始分布状态，并发现在高温条件下，由于流体包裹体的爆裂而导致花岗岩中微小裂纹的形成。在标准大气压条件下测定了流体包裹体的爆裂温度，研讨了其形状、尺寸、均质化温度等因素对爆裂温度的影响，并根据形态观察掌握了裂纹形成的基本规律。这些特征对于各类花岗岩具有一定的普遍性，能为掌握花岗岩在高温条件下的物理及力学性质提供重要的基础数据，对于高放射性核废料地下深部处理等工程问题具有较大的参考价值。     

Phylogenetic analysis of Beggiatoa spp. from organic rich sediment of Tokyo Bay, Japan

Nitrate-accumulating filamentous bacteria from organic rich sediment of Tokyo Bay, morphologically similar to Beggiatoa species, were phylogenetically analyzed. From several sites in Tokyo Bay, Beggiatoa-like bacteria were collected. Each sample contained narrower or wider type (10 and 30 microns, respectively) of trichomes. With the nested PCR using specific primers for Beggiatoa, fragments of 16S rRNA gene were amplified and then subjected to denaturing gradient gel electrophoresis (DGGE) analysis. Sequencing and the following phylogenetic analysis indicated that they are related to large Beggiatoa species. The wider type was related to uncultured Beggiatoa clones of other geographical localities and distinct from the narrower type in Tokyo Bay. Among the narrower types, a sample from a tidal flat was genetically distinct from the sample from sites of 10 and 20 m water depth. These narrower types form a new branch in Beggiatoa/Thioploca cluster. The result of phylogenetic analysis was in accordance with the previous studies that indicate possession of nitrate-accumulation capability is congruent with phylogeny based on 16S rRNA sequences.     

Removal of residual dissolved methane gas in an upflow anaerobic sludge blanket reactor treating low-strength wastewater at low temperature with degassing membrane

In this study, we investigated the efficiency of dissolved methane (D-CH₄) collection by degasification from the effluent of a bench-scale upflow anaerobic sludge blanket (UASB) reactor treating synthetic wastewater. A hollow-fiber degassing membrane module was used for degasification. This module was connected to the liquid outlet of the UASB reactor. After chemical oxygen demand (COD) removal efficiency of the UASB reactor became stable, D-CH₄ discharged from the UASB reactor was collected. Under 35 °C and a hydraulic retention time (HRT) of 10 h, average D-CH₄ concentration could be reduced from 63 mg COD L⁻¹ to 15 mg COD L⁻¹; this, in turn, resulted in an increase in total methane (CH₄) recovery efficiency from 89% to 97%. Furthermore, we investigated the effects of temperature and HRT of the UASB reactor on degasification efficiency. Average D-CH₄ concentration was as high as 104 mg COD L⁻¹ at 15 °C because of the higher solubility of CH₄ gas in liquid; the average D-CH₄ concentration was reduced to 14 mg COD L⁻¹ by degasification. Accordingly, total CH₄ recovery efficiency increased from 71% to 97% at 15 °C as a result of degasification. Moreover, degasification tended to cause an increase in particulate COD removal efficiency. The UASB reactor was operated at the same COD loading rate, but different wastewater feed rates and HRTs. Although average D-CH₄ concentration in the UASB reactor was almost unchanged (ca. 70 mg COD L⁻¹) regardless of the HRT value, the CH₄ discharge rate from the UASB reactor increased because of an increase in the wastewater feed rate. Because the D-CH₄ concentration could be reduced down to 12 ± 1 mg COD L⁻¹ by degasification at an HRT of 6.7 h, the CH₄ recovery rate was 1.5 times higher under degasification than under normal operation.