Suppression control method for torque vibration of three-phase HB-type stepping motor utilizing feedforward control

This paper proposes a method to reduce the vibration of the three-phase HB-type stepping motor with cogging torque by the feedforward compensation control. The compensation signal to suppress the vibration of the motor frame is obtained by the repetitive controller installing an online Fourier transformer and utilizing an acceleration sensor attached to the motor frame or an acoustic sensor such as a microphone placed close to the frame. The sensor is used only for the acquisition of the feedforward compensation data. The feedforward compensation signal at an arbitrary operating point is derived from the amplitude and phase data of the frequency components and the operating point data. Compensation data obtained by the repetitive controller is applied to the operating point changed by reference frequency and load condition in steady state. The compensation signal for the new operating point will be generated from compensation data utilizing polynomial equation approximation and linear interpolation method. The effectiveness of this proposed method is confirmed by the experimental results.     

Digitally tunable optical filters using arrayed-waveguide grating(AWG) multiplexers and optical switches

Two novel configurations for digitally tunable optical filters based on arrayed-waveguide grating (AWG) multiplexers are described in detail with emphasis on the connection of the AWG multiplexer and optical switches. Performance comparisons show that conventional configurations are disadvantaged by the switch size required and loss imbalance among the optical frequency-division-multiplexed (FDM) channels; the proposed configurations require only O(√(N)) switch elements to select one of N FDM channels, and the loss imbalance is lower by up to 75% in decibel     

Continuous hydrolysis of olive oil by lipase in microporous hydrophobic membrane bioreactor

Continuous hydrolysis of olive oil byCandida cylindracea’s lipase was studied in a microporous hydrophobic membrane bioreactor. Olive oil and buffer solution, fed continuously through two compartments partitioned by membrane, caused reaction at the interface of lipase-adsorbed membrane and buffer solution. Fatty acid was obtained in a single phase without being mixed with components of other phases. At all mean residence times, countercurrent flow mode was superior to cocurrent one. The lipase was adsorbed onto the membrane, and its adsorption was suggested to be partially specific from the experiments with enzymes having various levels of purity. The percent hydrolysis depended hyperbolically on the interfacial enzyme concentration. The hydrolysis seemed to be limited by diffusion of fat or fatty acid through the micropores of the membrane at higher interfacial enzyme concentrations. The lipase was stabilized significantly by glycerol added to the buffer solution. Satisfactory performance of the membrane bioreactor was obtained in a longterm continuous operation which lasted for 24 days by feeding buffer-glycerol (18.0%) solution over the adsorbed lipase. The operational half-life of the adsorbed enzyme was 15 days at 40 C.     

Modified Imidazoles: Degradation Inhibitors and Adhesion Promoters for Polyimide Films on Copper Substrates

Polyimide films on copper substrates that are exposed to elevated temperatures and an oxidizing environment will be subject to degradation. In order to halt this degradation without changing the properties of the system, a polymeric agent could be placed between the polyimide and the copper. This paper will investigate three such materials that will not only slow down the degradation of the polyimide and the oxidation of the copper, but will also improve adhesion within the system. Fourier transform infrared reflection-absorption spectroscopy (FTIR-RAS) will be used to investigate the polyimide/polymeric agent/copper system.     

A probabilistic simulator for population dynamics of quasispecies

We constructed a probabilistic simulator that allows all the events in population dynamics such as death, birth, mutation, and suppression/stimulation to be described by probabilistic rules. The simulator also facilitates a lattice used for expressing distribution and diversity (number of distinct strains) of quasispecies. The simulator is used to investigate the diversity threshold in HIV and T-cell interaction. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Identification of osteopontin in human dental calculus matrix

Osteopontin is a prominent non-collagenous component of bone matrix, although it is expressed in several other tissues. Recently, osteopontin was reported to be involved in urinary stone formation and atherosclerotic lesions of the aorta, suggesting that it may be a key protein associated with these types of pathological mineralization. In this study, whether or not human dental calculus contains osteopontin was investigated by immunoblotting and immunohistochemical analyses. After extraction of calculus proteins with EDTA and separation of the proteins by electrophoresis, immunoblotting analysis revealed the presence of osteopontin. Two forms of osteopontin appeared at 61 and 68 kDa on 10% polyacrylamide gel and the proteins were digested with thrombin, a highly specific protease. Moreover, immunohistochemical analysis revealed that osteopontin was localized in dental calculus adherent to tooth roots. These findings indicate that osteopontin is, in fact, present in human dental calculus and may be involved in calculus formation as the stone matrix.     

A dynamic Houjin (square) and a symmetric Houjin

A Houjin is an n by n square lattice with each cell containing a symbol (such as a number or a letter). Further, these numbers or letters are designed to exhibit symmetry. For example, a magic square is a Houjin where the embedded symmetry is that the numbers in each row, column, and a center diagonal have an equal sum. This article reports a new Houjin: a dynamic Houjin. A dynamic Houjin changes its numbers at each time step while satisfying the symmetry as a Houjin (a magic square). The dynamic Houjin has a further symmetry in a time dimension, i.e., the sums of the numbers in each cell are identical.     

Catalyzing the curing reaction of a new benzoxazine-based phenolic resin

The effect of potential catalysts on the curing reaction of a new type of phenolic resins obtained from benzoxazine precursors is studied. These novel resins solve the shortcomings of traditional phenolics because they cure by a ring-opening mechanism that avoids the release of volatiles. Isothermal and nonisothermal differential scanning calorimetry (DSC) data is used to determine the influence of the catalysts on the curing kinetics. Fourier transform infrared (FTIR) spectroscopy is also applied. The benzoxazine chosen for this study is a purified benzoxazine monomer based on bisphenol-A, formaldehyde, and aniline. The as-synthesized benzoxazine precursor is also studied to determine the influence of the dimers and higher oligomers in the curing mechanism. The presence of these structures seems to catalyze the curing reactions. The activation energy and overall reaction order of the as-synthesized precursor are determined. Among the catalysts tested, adipic acid shows the most promising results. For all the cases studied the curing reaction is autocatalyzed up to a diffusion-controlled stage. © 1995 John Wiley & Sons, Inc.