Development of a knowledge-based decision support system for diagnosing malfunctions of advanced production equipment

This paper presents a case study documenting the development of an expert system for diagnosing the malfunctions of a machine used by the NEC Corporation to mount chips on integrated circuit boards. Development of the expert system was justified by the inability of operators to efficiently diagnose many malfunctions of the chip-mounting machine, the associated cost of production delays, and the disruption incurred when experts were forced to leave unrelated tasks to help operators troubleshoot malfunctions. The first step in development of the expert system was to elicit and organize the machine designer's knowledge. This process resulted in a hierarchical classification of malfunction symptoms and causes, a set of 15 flow diagrams documenting the designer's troubleshooting procedures for particular malfunction symptoms, and a matrix documenting design information. The flow diagrams were translated into a large logic network diagram, which was directly translated into a set of 94 rules. An additional set of 270 rules were derived from the design matrix. The resulting 364 rules were then implemented in an expert system using the KES shell. On-site validation revealed that 92% of the chip-mounting machine's malfunctions occurring in 1988-1989 were successfully diagnosed by the expert system. Future directions of this research will be oriented toward the development of a general purpose expert system capable of diagnosing the malfunctions of other similar production equipment.     

氮硫掺杂介孔TiO2薄膜结构及其光催化性能

分别以Ti(OBuⁿ)₄和Pluronic F127为无机前驱体和模板剂, 以硫脲为添加剂, 采用sol-gel法结合蒸发致自组装法（EISA）制备了锐钛矿结构的介孔TiO₂薄膜材料.采用SEM、 XPS、N₂ 吸附-脱吸、XRD和 UV-Vis光谱对其进行了表征. 研究发现, 向前驱体溶液添加硫脲一方面改变了TiO₂的介孔结构, 另一方面对介孔TiO₂进行了N、S共掺杂. 当溶液中硫脲与Ti(OBuⁿ)₄的摩尔比为2.5%时, 介孔TiO₂的孔径由未掺杂的7.0nm增至12.4nm, 光催化降解甲基橙实验表明其在紫外光区具有最优的光催化活性; 当溶液中硫脲与Ti(OBuⁿ)₄的摩尔比为5%时, 其吸收边由380nm扩展至520nm, 光催化降解罗丹明B实验表明其在可见光下显示出最优的光催化活性.     

High Power Neutral Beam Injection in LHD

The results on high power injection with the ueutral bean, injection （NBI） system for the Large Helical Device （LHD） are reported. The system consists of three beam-lines with two hydrogen negative ion （H^- ion） sources installed in each beam-line. In order to improve the injection power, a new beam accelerator with a multi-slot grounded grid （MSGG） has been developed and applied to one beam-line. Using the accelerator, a maximum power of 5.7 MW was achieved in 2003 and 2004, and the maximum energy of 189 keV was reached. The power and energy exceeded the design values of the individual beam-line for LHD. The other beam-lines also increased their injection power up to about 4 MW, and the total injection power of 13.1 MW was achieved with three beam-llnes in 2003. Although the accelerator had an advantage in high power beam injection, extracted beams expand in the short side direction of the ground-grid slot. The disadvantage has been resolved by modifying the aperture shapes of the steering grid.     

ɛ-(γ-Glutamyl)lysine Crosslink Formation in Sardine Myofibril Sol during Setting at 25°C

The quantitative change of ?-(y-glutamyl)lysine (EGL) crosslink and relationship between crosslink content and gel-strength were examined on salt-ground myofibril sol from sardine (Sardinops melanostictus) during incubation at 25°C. In the presence of EGTA, no EGL crosslinks were detected in myofibril sol and gelation did not occur. The EGL crosslink content and breaking strength of gels increased in proportion to incubation time. High correlation was observed between the logarithm of breaking strength and logarithm of EGL crosslink content (r=0.987). The EGL crosslinks formed by transglutaminase are important in the setting of sardine meat sol at < 30°C.     

Inhibition of N-Nitrosamine Formation in a Cured Ground Pork Belly Model System

A model system consisting of a uniformly distributed sample of ground pork in conjunction with a nitrite containing curing solution was utilized to evaluate the formation of N-nitrosamines. Utilizing this system a wide variety of compounds were discovered to dramatically reduce the level of N-nitrosopyrrolidine (NPyr) formed during frying. Carbohydrates including the reducing sugars dextrose, ribose, lactose, and maltose, as well as liquid smoke preparations, were found to reduce NPyr levels by as much as 60%. In addition, when low levels of combinations of inhibitors glucose, liquid smoke, and α-tocopherol were incorporated, reductions in nitrosamine levels as great as 80% were observed in model systems as well as in pilot plant manufactured bacon.     

On Sodium Chloride Action in the Gelation Process of Low Density Lipoprotein (LDL) from Hen Egg Yolk

Gelation of 40% LDL solution with 1~10% NaCl was inhibited during frozen storage at ?20°C and ?25°C. Frozen storage of LDL solutions with more than 4% NaCl at ?30°C, ?40°C and ?60°C induced the gelation, whereas gelation was inhibited by addition of 1 and 2% NaCl at temperatures lower than ?30°C. Differential scanning calorimetry analyses revealed that when NaCl acts as an inhibitor of gelation, it increased the unfrozen water in the LDL solutions through formation of LDL-water-NaCl complex where the water is hardly frozen; and when it acts as an accelerator of gelation, it promoted removal of water from the complex.     

Improvement of solidification model and analysis of 3D channel blockage with MPS method

In a severe accident of a nuclear power reactor, coolant channel blockage by solidified molten core debris may significantly influence the core degradations that follow. The moving particle semi-implicit (MPS) method is one of the Lagrangian-based particle methods for analyzing incompressible flows. In the study described in this paper, a novel solidification model for analyzing melt flowing channel blockage with the MPS method has been developed, which is suitable to attain a sufficient numerical accuracy with a reasonable calculation cost. The prompt velocity diffusion by viscosity is prioritized over the prompt velocity correction by the pressure term (for assuring incompressibility) within each time step over the “mushy zone” (between the solidus and liquidus temperature) for accurate modeling of solidification before fixing the coordinates of the completely solidified particles. To sustain the numerical accuracy and stability, the corrective matrix and particle shifting techniques have been applied to correct the discretization errors from irregular particle arrangements and to recover the regular particle arrangements, respectively. To validate the newly developed algorithm, 2-D benchmark analyses are conducted for steady-state freezing of the water in a laminar flow between two parallel plates. Furthermore, 3-D channel blockage analyses of a boiling water reactor (BWR) fuel support piece have been performed. The results show that a partial channel blockage develops from the vicinity of the speed limiter, which does not fully develop into a complete channel blockage, but still diverts the incoming melt flow that follows to the orifice region.