Synthesis of continuous-time dynamic quantizers for LFT type quantized feedback systems

This paper focuses on analysis and synthesis methods of continuous-time dynamic quantizers for LFT type quantized control systems. Our aim is to propose a numerical optimization design method of multiple (decentralized) quantizers such that a given linear system is optimally approximated by the given linear system with the multiple quantizers. Our method is based on the invariant set analysis and the LMI technique. In addition, we clarify that our proposed method naturally extends to multiobjective control problems similar to linear control. For implementation, this paper presents an analysis condition of the applicable interval of switching process of quantizer. Finally, it is pointed out that the proposed method is helpful through a numerical example.     

Phase diagrams of confined solutions of dimyristoylphosphatidylcholine (DMPC) lipid and cholesterol in nanotubes

We have studied equilibrium morphologies of dimyristoylphosphatidylcholine lipid solution and cholesterol solution confined to nanotubes using dissipative particle dynamics (DPD) simulations. Phase diagrams regarding monomer concentration c versus radius of nanotube r for both solutions are attained. Three types of the inner surface of nanotubes, namely hydrophobic, hydrophilic, and hydroneutral are considered in the DPD simulations. A number of phases and molecular assemblies for the confined solutions are revealed, among others, such as the spiral wetting and bilayer helix. Several phases and assemblies have not been reported in the literature, and some are non-existence in bulk solutions. The ability to control the morphologies and self-assemblies within nanoscale confinement can be exploited for patterning interior surface of nanochannels for application in nanofluidics and nanomedical devices.     

Experimental study on slider dynamics during touchdown by using thermal flying-height control

To investigate the possibility of further lowering the clearance in head?Cdisk interface systems, slider dynamic behavior during a touchdown sequence with a thermal flying-height control (TFC) function was investigated by using a spinstand-level evaluation utilizing an acoustic emission (AE) sensor and a laser Doppler vibrometer (LDV). Experimental results demonstrated that off-track vibration was easier to excite by head?Cdisk contact at the beginning of head?Cdisk contact. We then confirmed that the amplitude of pitch-mode vibration in the flying-height direction increased and sway-mode vibration in the off-track direction decreased when increasing heater power during the touchdown sequence. Moreover, we found that the peak frequency of pitch-mode vibration shifted to a higher frequency under over-push conditions. Time?Cfrequency domain analysis results showed that the peak shift occurred at several locations during a disk rotation. The mechanism of the peak shift is attributed to the increase in stiffness at the head?Cdisk interface (HDI) due to solid?Csolid contact or mode change occurred in such regions. During the touchdown sequence, the friction force at the HDI continues to increase, even though slider vibration and AE signal decrease when heater power is increased. The friction force at the HDI needs to be decreased to achieve further low-clearance HDI.     

Construction and development of a time-resolved x-ray magnetic circular dichroism-photoelectron emission microscopy system using femtosecond laser pulses at BL25SU SPring-8

A femtosecond pulsed laser system has been installed at the BL25SU soft x-ray beamline at SPring-8 for time-resolved pump-probe experiments with synchronization of the laser pulses to the circularly polarized x-ray pulses. There are four different apparatuses situated at the beamline; for photoemission spectroscopy, two-dimensional display photoelectron diffraction, x-ray magnetic circular dichroism (XMCD) with electromagnetic coils, and photoelectron emission microscopy (PEEM). All four can be used for time-resolved experiments, and preliminary investigations have been carried out using the PEEM apparatus to observe magnetization dynamics in combination with XMCD. In this article, we describe the details of the stroboscopic pump-probe XMCD-PEEM experiment, and present preliminary data. The repetition rate of the laser pulses is set using a pulse selector to match the single bunches of SPring-8's hybrid filling pattern, which consists of several single bunches and a continuous bunch train. Electrons ejected during the bunch train, which do not provide time-resolved signal, are eliminated by periodically reducing the channel plate voltage using a custom-built power supply. The pulsed laser is used to create 300 ps long magnetic field pulses, which cause magnetic excitations in micron-sized magnetic elements which contain magnetic vortex structures. The observed frequency of the motion is consistent with previously reported observations and simulations.     

Spectrometer for lanthanides' K x-ray fluorescence

X-ray fluorescence analysis is a highly useful technique for determining the chemical composition of matter. The present article describes the successful development of a wavelength-dispersive x-ray fluorescence spectrometer for a fairly high-energy range, 30-60 keV, that can contribute to studying lanthanides' Kbeta spectra with high-energy resolution. By combining a new high-energy synchrotron light source and the present spectrometer, it has been demonstrated that the full width at half maximum for lanthanum's Kbeta(1) is 32 eV and that all the peaks in the spectra are fully resolved. This corresponds to an energy resolution EDeltaE of 1180, which is ten times better than a conventional system based on a Ge detector, which can detect only two peaks, Kbeta(1) and Kbeta(2), in seven peaks. The present spectrometer can open up a new field in x-ray spectrometry.     

A solid-state Marx generator driven Einzel lens chopper

A new type of pulse chopper called an Einzel lens chopper is described. An Einzel lens placed immediately after an electron cyclotron resonance ion source is driven by high-voltage pulses generated by a newly developed solid-state Marx generator. A rectangular negative barrier pulse-voltage is controlled in time, and the barrier pulse is turned on only when a beam pulse is required. The results of successful experiments are reported herein.     

Friction characteristics of inorganic or organic thin coatings on solid surfaces under water lubrication

Water has been considered as an alternative working fluid for hydraulic power systems in order to minimize the consumption of fossil fuels and mineral oils. In spite of the many advantages to this use of water, difficult technical problems remain. The key technology for establishing a water hydraulic system is tribology, because water has a lack of lubricity, and thus some coating is needed to protect the metal surfaces from corrosion and frictional wear when using water as a lubricant. It has already been demonstrated that some Si-containing materials have good lubricity in a water environment. Recently, it has been shown that diamond-like carbon (DLC) coatings also have good lubricity with water. In order to clarify the mechanism by which such materials are lubricated with water, and to develop surface coatings that have good lubricity with water, the friction characteristic of several coated metals were investigated in this study. Coatings of CrN, CrSiN, and two types of DLC were applied on an SUS630 stainless steel flat disk substrate. Additive-free distilled water was used as a lubricating fluid. The friction characteristics of these coatings at different sliding speeds were evaluated using a tribometer with two contact configurations in which stainless steel balls and a flat ring without coatings were used as mating specimens.In addition, the lubrication characteristics of organic hydro-gels such as alginic acid or its metal salt were studied by immobilizing them on the surface, and their effects on the lubrication with water were discussed.     

Automated identification of partially exposed metal object

This paper describes a method for automated shape and pose (position and orientation) identification of partially exposed metal objects that enables safe and efficient excavation of hazardous materials. The method estimates the object pose by matching a model of the object with the area that is extracted from the range image using the characteristics of metal objects. The paper introduces a method for an initial search area for object matching in order to obtain the accurate shape and pose of the partially exposed objects with reasonable calculation time. The experimental results show feasibility of the shape and pose identification of partially exposed objects.     

A Nifedipine Coground Mixture with Sodium Deoxycholate. I. Colloidal Particle Formation and Solid-State Analysis

Sodium deoxycholate (DCNa) is a bile salt that forms multimolecular inclusion compounds with a variety of organic substances. In this study, complex formulation of DCNa with nifedipine, a poorly water soluble drug, by grinding was investigated. The coground mixture was prepared with a vibration rod mill, and its solid state was characterized using powder X-ray diffraction, differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. A laser diffraction particle size analyzer was also used to determine the particle size distribution curve in solution. When a nifedipine-DCNa (1:2 w/w) mixture coground for 30 min was dispersed into water and a pH 6.8 buffer solution, a semitransparent colloidal solution occurred immediately; 90% of the total particles formed in solution had a diameter less than 600 nm. Both powder X-ray diffraction peaks and DSC endothermic peak of nifedipine crystals were not found for the coground mixture, whereas a new exothermic peak was observed on DSC thermograms. The magnitude of this exothermic peak depended on the weight fraction of DCNa and the grinding time, indicating that nifedipine crystals changed into an amorphous state by complex formation with DCNa during the grinding process. In the FTIR spectrum of the coground mixture, the peaks of aromatic CH out-of-plane bend and dihydropyridine NH stretch of nifedipine were considerably weakened, suggesting that van der Waals interaction may be present between the drug and DCNa molecules. From these results, it is clear that the cogrinding method with DCNa is very useful for the formation of amorphous nifedipine in the solid state and the production of colloidal particles of the drug in solution.     

An Algorithm for Connected-Component Labeling, Hole Labeling and Euler Number Computing

Labeling connected components and holes and computing the Euler number in a binary image are necessary for image analysis, pattern recognition, and computer (robot) vision, and are usually made independently of each other in conventional methods. This paper proposes a two-scan algorithm for labeling connected components and holes simultaneously in a binary image by use of the same data structure. With our algorithm, besides labeling, we can also easily calculate the number and the area of connected components and holes, as well as the Euler number. Our method is very simple in principle, and experimental results demonstrate that our method is much more efficient than conventional methods for various kinds of images in cases where both labeling and Euler number computing are necessary.