Nanometer stepping drives of surface acoustic wave motor

High resolution (from nanometer to subnanometer) stepping drives of a surface acoustic wave motor are presented. It was shown that step displacement was easily controlled by adjusting a number of driving waves, using a steel ball slider equipped with permanent magnet for preload. By means of this open loop control, the step displacement was controlled from centimeter-order to submicrometer-order. In this paper, using a silicon slider equipped with a ball bearing linear guide, the stepping motions of a surface acoustic wave motor were investigated. A laser interferometer equipped with a 2-picometer resolution displacement demodulator was introduced. Motions of the slider ranging from several hundreds of nanometers to several nanometers in each step displacement were observed. Reduction of the driving waves down to 25 cycles, under a 100 V/sub peak/ driving voltage and a 30 N preload condition, generated about 2 nm stepping motion using our experimental setup under an open loop condition. We also demonstrated subnanometer step movements. These experimental results indicated that the surface acoustic wave motor has an ability of subnanometer positioning with a centimeter-level stroke.     

Characterization of the physicochemical properties of the micelles of platelet-activating factor (C18:0)

The purpose of this study was to clarify the physicochemical properties of the micelles of platelet-activating factor (PAF; C_18:0). The critical micelle concentration (CMC) of PAF (C_18:0) was determined (0.20 μM) using fluorescence techniques. The fluidity and the micropolarity of the PAF (C_18:0) micelle were similar to those of the micelle of stearoyl lysophosphatidylcholine.     

Comparison of the effect of lipid A analog E5531 and the lipid A from Escherichia coli on phospholipid membrane properties

The effect of the lipid A analog E5531 on the phospholipid membrane was compared with that of the lipid A from Escherichia coli (EC). E5531 decreased the phase transition temperature of dipalmitoylphosphatidylcholine (DPPC) membrane and increased the fluidity and micropolarity. On the other hand, the effect of EC on the membrane was contradictory. These results suggested that the reason for the difference of biological effects of these two lipid A would be caused by the differences from the effect on the cell membranes.     

A 100-mega-access per second matching memory for a data-drivenmicroprocessor

A high-throughput matching memory (MM) for a data-driven microprocessor is discussed. An MM can be constructed using a hashing memory. However, one of the biggest problems with hashing memory is the necessity for selective processing whenever hashed address conflicts occur. To eliminate this problem, the MM incorporated a small amount of associative memory (32 words×50 b) as well as the hashing memory (512 words×42 b). The matching operation is subdivided into three pipeline stages, all controlled by the elastic pipeline scheme. With this structure, an MM with a high throughput of 100-mega-access/s MM can be realized     

Thermodynamic analysis of the phase transition of polyethylene under high pressure

Mechanism of emergence of high pressure phase of polyethylene is analysed on the thermodynamic stand point: The change in free energy due to pressure increase is calculated for each phase on the basis of the experimental data. The transition temperature and melting point under the increased pressures are estimated and the results obtained are consistent with the observed values.     

GaAs 256-bit static RAM

A GaAs 256×1-bit static RAM with 2000 FETs organised in E/D-type DCFL circuits was successfully fabricated. A planar device structure was realised by using selective ion implantation and dielectric intermediate lift-off technology. The access time and the power dissipation were 50 ns and 9.4 mW, respectively.     

Phosphorylation of cellulose with phosphorous acid and thermal degradation of the product

The reaction of cellulose with phosphorous acid in molten urea afforded a white, water-soluble product. The product was a monoester of phosphorous acid, and all the phosphorus residues were in phosphonic form, i.e., cellulose phosphonate. Quantitative addition of acrylonitrile to the P? H bonds in cellulose phosphonate occurred in the presence of sodium ethoxide. By alkali hydrolysis of the adduct, a polyelectrolyte having two different ionization groups, P? OH and COOH, could be prepared. Thermal degradation of three cellulose phosphonates, ammonium cellulose phosphonate (I), ammonium cellulose 2-cyanoethlyphosphonate (II), and ammonium cellulose 2-carboxyethylphosphonate (III), was examined. All three samples decomposed at a temperature around 270°C, but their thermal behaviors were different. Replacement of hydrogen in the phosphonic residue by 2-cyanoethyl and 2-carboxyethyl groups retarded dehydration of cellulose. Sample I had a satisfactory flame retardance; samples II and III were not flame resistant. Reduction of flame retardance may be due to the electron-withdrawing effect of the cyano and carboxyl groups.     

Turbulent fluid flow phenomena in metals processing operations: Mathematical description of the fluid flow field in a bath caused by an impinging gas jet

A mathematical representation is developed for describing the flow field in liquids or melts, agitated by a symmetrically placed impinging gas jet. The problem is formulated by the statement of the axi-symmetrical turbulent fluid flow equations using the Prandtl-Komogorov model for the eddy viscosity. The resultant differential equations are solved numerically and the computed results are shown to be in reasonable agreement with experimental data reported in the literature. This problem is thought to be relevant to various metals refining operations and the results should also be helpful for the interpretation of laboratory scale studies in which molten metals are contacted with impinging gas jets.     

A new approach for solving singular systems in topology optimization using Krylov subspace methods

In topology optimization, elements without any contribution to the improvement of the objective function vanish by decrease of density of the design parameter. This easily causes a singular stiffness matrix. To avoid the numerical breakdown caused by this singularity, conventional optimization techniques employ additional procedures. These additional procedures, however, raise some problems. On the other hand, convergence of Krylov subspace methods for singular systems have been studied recently. Through subsequent studies, it has been revealed that the conjugate gradient method (CGM) does not converge to the local optimal solution in some singular systems but in those satisfying certain condition, while the conjugate residual method (CRM) yields converged solutions in any singular systems. In this article, we show that a local optimal solution for topology optimization is obtained by using the CRM and the CGM as a solver of the equilibrium equation in the structural analysis, even if the stiffness matrix becomes singular. Moreover, we prove that the CGM, without any additional procedures, realizes convergence to a local optimal solution in that case. Computer simulation shows that the CGM gives almost the same solutions obtained by the CRM in the case of the two-bar truss problem.