Realization of acceleration control using multirate sampling method

This paper focuses on the realization of high‐performance motion control based on acceleration control. The characteristics of acceleration control are investigated and the relationship between the performance and sampling frequency of the system is discussed. This paper then describes that a higher sampling frequency is required for acquisition of output information than for updating the input value. Based on this idea, a new multirate sampling method for an acceleration control system is proposed. A disturbance observer for the multirate system is designed by adopting a new definition of disturbance torque. A bilateral system is introduced as a preeminent example of a system that requires robust acceleration control. Both simulations and experiments are performed on the system, and the validity of the proposition is verified by the results. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(4): 72–81, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20507     

Temperature distribution in a workpiece during cylindrical plunge grinding

In cylindrical plunge grinding, a large amount of heat flows into the workpiece continuously, accumulates and remains even after the process, which causes dimensional error. Therefore it is necessary to investigate the temperature distribution in the workpiece during grinding and analyze the influence of grinding heat on the dimension. Such an investigation has not been done enough, because the technology to measure the temperature distribution in the rotating workpiece has not matured. Considering such background, an in-process measuring system has been developed, which makes it possible to detect the temperature distribution in a wide range from the outer surface to the inside of the rotating workpiece. The system consists of small temperature sensors which are embedded into the workpiece, a micro computer attached on the workpiece which acquires the data from the sensors and transmits to a personal computer by a wireless communication device. Furthermore the contact type thermocouple which enables to measure the rotating surface temperature is added to the system. Measurement experiments revealed that the grinding heat conducts from the workpiece surface toward the center, accumulates, and remains in the workpiece even after the process. Heat conduction simulation was also performed. Good agreement was achieved between the simulated temperatures and experimental measurements.     

Dispersion of single-walled carbon nanotubes in water by the use of novel fluorinated dendrimer-type copolymers

New fluorinated dendrimer-type block copolymers were applied to the dispersion of single-walled carbon nanotubes (SW-CNTs) and single-walled carbon nanotubes containing carboxy groups [(SW-CNT)-COOH] in water. Fluorinated block copolymer could disperse SW-CNTs more effectively in water, compared to that of the corresponding ABA triblock-type fluoroalkyl end-capped dimethylacrylamide oligomer [R_F-(DMAA)_n-R_F]. Dynamic light-scattering (DLS) measurements and transmission electron microscopy (TEM) images show that SW-CNTs could be smoothly encapsulated into fluorinated copolymeric aggregates cores. Interestingly, it was demonstrated that SW-CNTs could be in part released from the fluorinated copolymeric aggregates/SW-CNTs composites or encapsulated into these composites with increasing the dispersion times. On the other hand, fluorinated block copolymer and R_F-(DMAA)_n-R_F oligomer were not able to disperse well (SW-CNT)-COOH in water; however, ABA triblock-type fluoroalkyl end-capped acrylic acid oligomer was able to disperse quite effectively (SW-CNT)-COOH in water.     

KBO Orientability

This article presents three new approaches to prove termination of rewrite systems with the Knuth–Bendix order efficiently. The constraints for the weight function and for the precedence are encoded in (pseudo-)propositional logic or linear arithmetic and the resulting formula is tested for satisfiability using dedicated solvers. Any satisfying assignment represents a weight function and a precedence such that the induced Knuth–Bendix order orients the rules of the encoded rewrite system from left to right. This means that in contrast to the dedicated methods our approach does not directly solve the problem but transforms it to equivalent formulations for which sophisticated back-ends exist. In order to make all approaches complete we present a method to compute upper bounds on the weights. Furthermore, our encodings take dependency pairs into account to increase the applicability of the order. The first and third authors are supported by FWF (Austrian Science Fund) project P18763 and the second author is supported by the Grant-in-Aid for Young Scientists 20800022 of the Ministry of Education, Culture, Sports, Science and Technology of Japan.     

Development of mechanoluminescent micro-particles Ca2MgSi2O7:Eu,Dy and their application in sensors

We have revealed that Ca₂MgSi₂O₇:Eu micro-particles emits green light under the application of a mechanical stress, called as mechanoluminescence (ML). The ML showed a similar spectrum as photoluminescence (PL), which indicated that ML is emitted from the same center of Eu²⁺ ions as PL. Such a green light of ML emission can be seen by the naked eye when pressing the sample. Furthermore, using lab-made AFM-ML system, the ML of single micro-particle under the application of micro force (10 μN) has been investigated.     

熔铁催化剂活性与其母体铁氧化物形态和组成的关系(Ⅱ) 表面活性位和氨合成反应速率

采用N2 低温吸附、CO和CO2 化学吸附技术和活性试验研究了不同铁氧化物为母体的氨合成催化剂表面活性位与催化活性的关系 .结果表明 ,活性相铁原子在表面的暴露百分数 <1 % ,99%以上的铁原子掩埋在体相内部 .随着母体铁氧化物性质和组成的变化 ,催化剂活性 (以氨的体积分数表征 )、质量反应速率 (rm)、合成氨转换频率 (TOF)和表面酸覆盖度 (SA)及其酸碱覆盖度的比例 (SA/SK)有相似的变化规律 ,即与Fe2 +/Fe3+呈驼峰形变化曲线 .实验发现 ,随着母体中FeO含量的增加 ,还原后催化剂表面性质和表面结构改变 ,表面活性位数目减少而活性位强度增大 .这可能是结构改性剂Al2 O3对Fe晶面的表面重构作用所致 .     

A model-based sound localization system and its application to robot navigation

This paper describes a mobile robot equipped with a real time sound localization system as well as a sonar system for obstacle detection. The sound localization method is based on a model of the precedence effect of the human auditory system to cope with echoes and reverberations. Sound localization and robot navigation experiments were conducted. The results show that the robot is capable of localizing sounding objects in a reverberant environment and approaching the objects without collisions, even when the objects were behind obstacles. Environment flexibility and error robustness of the system were discussed as well.     

Study on a reversible thermal panel for spacecraft (detailed design based on parametric studies and experimental verification)

This paper describes a new passive thermal control device—a Reversible Thermal Panel (RTP), which changes its function reversibly from a radiator to solar absorber by deploying/stowing the radiator/absorber reversible fin. Parametric studies were conducted and the RTP configuration which satisfies the thermal requirements was determined. The RTP engineering model was fabricated using highly oriented graphite sheets, honeycomb base plate, and shape memory alloy. The heat rejection performances and autonomous thermal controllability were evaluated by thermal vacuum tests. The test results show the excellent performances of heat rejection, absorption, and autonomous thermal control for the RTP. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(7): 464–481, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20131     

Passive emission colorimetric sensor (PECS) for measuring emission rates of formaldehyde based on an enzymatic reaction and reflectance photometry

A coin-sized passive emission colorimetric sensor (PECS) based on an enzymatic reaction and a portable reflectance photometry device were developed to determine the emission rates of formaldehyde from building materials and other materials found indoors in only 30 minutes on-site. The color change of the PECS linearly correlated to the concentration of formaldehyde aqueous solutions up to 28 microg/mL. The correlation between the emission rates measured by using the PECS and those measured by using a desiccator method or by using a chamber method was fitted with a linear function and a power function, and the determination coefficients were more than 0.98. The reproducible results indicate that the emission rates could be obtained with the correlation equations from the data measured by using the PECS and the portable reflectance photometry device. Limits of detection (LODs) were 0.051 mg/L for the desiccator method and 3.1 microg/m2/h for the chamber method. Thus, it was confirmed that the emission rates of formaldehyde from the building materials classified as F four-star (< 0.3 mg/L (desiccator method) or < 5.0 microg/m2/h (chamber method)), based on Japanese Industrial Standards (JIS), could be measured with the PECS. The measurement with PECS was confirmed to be precise (RSD < 10%). Other chemicals emitted from indoor materials, such as methanol, ethanol, acetone, toluene, and xylene, interfered little with the measurement of formaldehyde emission rates by using the PECS.     

节杆菌β-1,3葡聚糖内切酶的分离纯化与特性研究

通过硫酸铵沉淀、阴离子交换层析和柱层析从节杆菌（Arthrobacter sp．）粗酶制剂分离纯化得到β-1,3葡聚糖内切酶。经SDS凝胶电泳和柱层析测得纯化酶为单体酶,分子量为32．5kDa;纯化酶N末端的10个氨基酸序列为APGDLLWSDE,在pH5～8之间稳定,最适pH6．5,最适温度55℃,但50℃以上失活很快。纯化酶对昆布4,5,6,7糖及昆布多糖底物的米氏常数分别为0．12,0．11,0．067,0．066mM和0．16mg／mL,也可水解热凝胶和地衣多糖,葡糖苷内切酶H（Streptomyces griseus）不能分解它,证明该酶不含糖基。该酶属于糖基水解酶16族系。