Signal Representation by Adaptive Biased Wavelet Expansions

This paper reviews a technique of adaptive wavelet expansions and introduces the novel concept of “biased wavelets.” These are functions that are localized in time and in frequency but, unlike conventional wavelets, have an adjustable nonzero mean component. Under mild conditions, it is shown that a conventional mother wavelet can be used to construct a family of biased wavelets which spans the set of finite-energy functions L²( ). Numerical tests suggest that the introduction of the adjustable “bias” considerably improves the representation capabilities of wavelet expansions. A problem of electrocardiographic data compression is used for illustration purposes. Test signals were extracted from the MIT–BIH ECG Compression Test Database.     

Anisotropic orthodontic force from the hollow super-elastic Ti-Ni alloy wire by transforming the wire cross-section

The purpose of this research was to devise a method for transforming the cross-section of the hollow super-elastic Ti-Ni alloy round wire and to examine the changes in its bending properties for clinical orthodontic application. The specimen wires were pressed with the use of heated pliers to transform the cross-sectional shape. As a result, transformation of the wire cross-section with super-elasticity was possible. As a verified by cantilever test and three-point bending test of the transformed specimens, a two-dimensional orthodontic force, which was different in each bending direction, was obtained. The hollow wire showed considerably high load level in the long axis along with markedly low load level in the short axis, which was mainly caused by the change in the moment of inertia by transforming the cross-section. It was revealed that, by transforming the wire cross-section of the hollow super-elastic Ti-Ni alloy round wires, anisotropic orthodontic force in bending properties could be obtained with super-elasticity.     

Influence of aging heat treatment on mechanical properties of biomedical Ti–Zr based ternary alloys containing niobium

Titanium–zirconium based alloys containing a small amount of niobium were investigated in order to evaluate their possible use as biomedical materials. Zirconium, which belongs to the IVa group, is known to have good corrosion resistance and biocompatibility similar to titanium. As the titanium–zirconium system shows a complete solid solution, a wide variation of alloy design is available and large quantities of solid-solution hardening must be possible. Niobium, having a -phase stabilizing effect, was chosen as a ternary element in order to control desirably the microstructure. There have been no reports which suggest its harm to a living body. The alloys containing 2% or 3% niobium showed the highest hardness value after aging heat treatment at 773 K. In contrast to this, no alteration of hardness was seen in specimens aged at 1073 K. Through conventional X-ray diffractometry and in situ X-ray analysis using a hot stage, -phase precipitation in the A matrix was identified. From the above results, it is concluded that alloys containing 2%–3% niobium are hopeful candidates for new kinds of biomedical alloys, when they are heat treated under suitable conditions. © 1998 Kluwer Academic Publishers     

Evaluation of sludge properties in a pilot-scale UASB reactor for sewage treatment in a temperate region

In this study, continuous operation of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor for sewage treatment was conducted for 630 days to investigate the physical and microbial characteristics of the retained sludge. The UASB reactor with a working volume of 20.2 m(3) was operated at ambient temperature (16-29 °C) and seeded with digested sludge. After 180 days of operation, when the sewage temperature had dropped to 20 °C or lower, the removal efficiency of both total suspended solids (TSS) and total biochemical oxygen demand (BOD) deteriorated due to washout of retained sludge. At low temperature, the cellulose concentration of the UASB sludge increased owing to the rate limitation of the hydrolytic reaction of suspended solids in the sewage. However, after an improvement in sludge retention (settleability and concentration) in the UASB reactor, the process performance stabilized and gave sufficient results (68% of TSS removal, 75% of total BOD removal) at an hydraulic retention time (HRT) of 9.7 h. The methanogenic activity of the retained sludge significantly increased after day 246 due to the accumulation of Methanosaeta and Methanobacterium following the improvement in sludge retention in the UASB reactor. Acid-forming bacteria from phylum Bacteroidetes were detected at high frequency; thus, these bacteria may have an important role in suspended solids degradation.     

Scanning Tunneling Microscopy Study of the Anomalous Metallic Phases in θ-(BEDT-TTF)2 MZn(SCN)4 (M= Rb, Cs)

We have studied metallic phases of the title organic conductors by means of STM at room temperature. An image obtained in the salt with M=Rb is very different from a typical one in the salt with M=Cs. We suggest “vertical stripe” charge ordering in the salt with M=Rb at room temperature, which can naturally explain its anomalous metallic behavior.     

New Robust Stability Conditions and Design of Robust Stabilizing Controllers for Takagi–Sugeno Fuzzy Time-Delay Systems

In this paper, we consider robust stability and stabilization of uncertain Takagi-Sugeno fuzzy time-delay systems where uncertainties come into the state and input matrices. Some stability conditions and robust stability conditions for fuzzy time-delay systems have already been obtained in the literature. However, those conditions are rather conservative and do not guarantee the stability of a wide class of fuzzy systems. This is true in case of designing stabilizing controllers for fuzzy time-delay systems and it thus leads to a conservative fuzzy controller design as well. We first consider rather relaxed robust stability conditions of uncertain fuzzy systems. To this end, we introduce an auxiliary system to the original fuzzy time-delay system to obtain generalized delay-dependent stability conditions. Such an auxiliary system has some arbitrary matrices that generalize not only the system representation but also delay-dependent stability conditions. Conditions we obtain here are delay-dependent conditions that depend on the upper bound of time-delay, and are given in terms of linear matrix inequalities (LMIs). Then, we compare our delay-dependent stability conditions with other conditions in the literature, and show that our conditions guarantee the stability of a wider class of systems than others. Next, we consider the robust stabilization problem with memoryless and delayed state feedback controllers. Based on our generalized robust stability conditions, we obtain delay-dependent sufficient conditions for the closed-loop system to be robustly stable, and give a design method of robustly stabilizing controllers. Finally, we give three examples that illustrate our results.     

Inter-laboratory validation studies of analytical method for determination of chloramphenicol in royal jelly

Inter-laboratory validation studies were conducted in 6 laboratories to validate the analytical method for determination of chloramphenicol in royal jelly. Chloramphenicol spiked at the levels of 0.1 and 0.5 ppm was analyzed. Mean recoveries were 89 and 89%, reproducibility relative standard deviations (RSD(R)) were 10.5 and 6.8%, HORRAT(R) values were 0.5 and 0.4. Samples containing residues at the levels of 0.25 and 0.80 ppm were analyzed. Mean recoveries were 89 and 84%, RSD(R) were 9.8 and 12.3%, and HORRAT(R) values were 0.5 and 0.7. The determination limit was 0.05 ppm. These results show that this method has good performance.     

Effects of heat-degraded sugars on survival and growth of Vibrio parahaemolyticus and other bacteria

We studied the effects of autoclaved (121 degrees C, 15 min) sugar solutions on the survival and growth of Vibrio parahaemolyticus and other bacteria. The growth and survival of V. parahaemolyticus in Luria-Bertani media and phosphate buffer, respectively, were inhibited by the addition of D-glucose autoclaved in pH 8.0 phosphate buffer. The bactericidal effect of autoclaved D-glucose was very small when autoclaved in pH 7.0 phosphate buffer, but larger effects were observed when autoclaved in the buffer at an alkaline pH. The autoclaving of D-glucose in CH3COONa, NaHCO3, and Na2HPO4 solutions at pH 7.6 to 8.5 also generated bactericidal effects, but it was not the case when D-glucose was autoclaved in Na2SO4, (NH4)2SO4, or NH4Cl solution at pH 8.0. The same effects as autoclaved D-glucose were observed in autoclaved lactose, D-fructose, and D-ribose. The bactericidal effects of autoclaved D-glucose were also noted in Salmonella Enteritidis, Listeria monocytogenes, and E. coli strains, but the effects were smaller than those seen in V. parahaemolyticus and V. vulnificus. The growth of V. parahaemolyticus in clam extracts was also inhibited by the addition of autoclaved D-glucose, indicating that heat-treated reduced sugars can exert bactericidal effects in foods.     

Starting Procedure of Rotational Sensorless PMSM in the Rotating Condition

This paper investigates a starting procedure of rotational sensorless permanent magnet synchronous motor (PMSM) in the rotating condition, which is suitable for some applications with higher maximum rotor frequency and longer current sampling time. Instantaneous estimation of initial rotor position and frequency, right after gates start, is essential for restarting the operation of inverters. Existing estimation methods are not available for the aforementioned applications because of their higher maximum rotor frequency and longer current sampling time. To cope with this problem, we propose a novel initial rotor frequency estimation method. The proposed estimation method is verified by experiments using a 2-kW interior PMSM and a numerical simulation.     

Differential precoder IC modules for 20-and 40-Gbit/s opticalduobinary transmission systems

This paper reports on 20- and 40-Gbit/s differential precoder modules for optical duobinary transmission systems. These precoder modules overcome the speed limit of a conventional precoder by parallel processing. The proposed precoders handle two or four parallel signals before multiplexing with data rates of one-half or one-quarter the transmission bit rate, and the final preceded signal is obtained by multiplexing the precoder output bit by bit, production-level 0.2-μm gate-length GaAs MESFET's were used to fabricate the precoders. The precoders are mounted in an RF package. They successfully performed 20- and 40-Gbit/s precoding for the first time, and the 20-Gbit/s precoder achieved a maximum precoding rate of 22 Gbit/s, which is 76% faster than that of the conventional circuit using the same MESFETs. The 40-Gbit/s precoder performs 40-Gbit/s precoding when combined with a 40-Gbit/s multiplexer unit. Twenty-Gbit/s optical duobinary transmitter and receiver circuits using the 20-Gbit/s precoder module successfully generate fully encoded optical duobinary signal at this rate for the first time. These circuits show a receiver sensitivity of -28.6 dBm for a bit error rate of 1×10^-9