Analysis of plastic bending of adhesive-bonded sheet metals taking account of viscoplasticity of adhesive

The present authors proposed a new technique of plastic bending of adhesive-bonded sheet metals. In this process, large transverse shear deformation occurs in the adhesive layer, which in some cases would induce the geometrical imperfection (so-called ‘gull-wing bend’) and the delamination. Since the strength of the adhesive is highly rate-sensitive, the amount of shear deformation of the adhesive layer and, as a result, ‘gull-wing bend’, are strongly influenced by the forming speed. In the present work, the effect of forming speed on the deformation characteristics of adhesively bonded aluminium sheets was investigated by performing V-bending experiments with various punch speeds at room temperature. In order to discuss the effect quantitatively, the numerical simulations for the bending were also conducted using a rate-dependent constitutive model of plasticity for the adhesive. Consequently, it was found that the large shear deformation and ‘gull-wing bend’ are suppressed by high-speed forming since the deformation resistance becomes higher at high strain rate.     

A micropipette system based on low driving voltage carbon nanotube actuator

Microsystem Technologies - We have fabricated a pipette system driven by a carbon nanotube (CNT) electroactive polymer (EAP) actuator, equipped with commercially available two- and three-way...     

Polymeric reaction of acrylic polymer–monomer system irradiated by low energy electron beam. I. Effects of molecular weight of polymer and polymer-to-monomer ratio

Polymeric reaction of the poly(n-butyl acrylate) (PBA)–benzyl acrylate (BzA) system induced by a low-energy electron beam was investigated. In order to elucidate the reaction behavior of the PBA–BzA system, the gel fraction, molecular weight of soluble part, and molecular weight distributions were examined by means of gel permeation chromatography (GPC) equipped with both ultraviolet (UV) and refractive index (RI) detectors. RI-detected GPC curves represented the molecular weights and their distributions of the total polymers, graft polymer, homopolymer, and unreacted PBA, while UV-detected curves only corresponded to the benzyl groups of graft polymer and homopolymer. Thus, the reaction behavior of the system was able to be followed by GPC. The molecular weight of the added PBA and the mole ratio of PBA/BzA were varied. The crosslinking, the graft reaction and the homopolymerization of BzA proceeded competitively during the polymeric reaction. The proportions of BzA unit incorporated into the crosslinked, graft and homo polymers were estimated by combining of measurement of gel fraction, UV-detected GPC curves, and infrared (IR) spectrum of gel. It was revealed that in the system containing PBA with high molecular weight, the grafting, and the crosslinking reactions predominated. The main reaction was the grafting in the system with a high mole ratio of PBA/BzA, while it was the homopolymerization in the systems with the low mole ratio of PBA/BzA. The reaction mechanism is discussed on the basis of reactivity and mobility of polymer radicals.     

High-speed processing in wired-and-wireless integrated autonomous decentralized system and its application to IC card ticket system

The automatic fare collection systems need both high performance and high reliability. High performance is one of the most expected functions on the automatic fare collection gates (AFCGs) handling the highly dense passengers during rush hours. Reliability is also indispensable because the tickets are equivalent to money. For a wireless IC card ticket system, expected to improve the passengers’ convenience and to reduce the maintenance cost, is difficult to meet these two requirements because of wireless communications between an IC card and an AFCG. This paper introduces the autonomous decentralized system as the solution and how it is applied to the system. Then, two models are prepared and simulated to evaluate the efficiency, especially high-speed processing. The technologies are implemented into the “Suica” system at East Japan Railway Company and have proven the effectiveness.     

A Novel Measurement Method for the Simultaneous Estimation of Specific Heat Capacity and Thermal Conductivity

A novel method is proposed for the simultaneous calculation of thermal conductivity κ and specific heat capacity C. The new method is a combination of two established techniques. One is the photopyroelectric method for thermal diffusivity α and the other is the front-heat front-detection photothermoreflectance method for thermal effusivity b. After α, b, and density ρ measurements, C and κ are easily calculated as C?=?b α ^?1/2 ρ ^?1 and κ =?α ^1/2 b. Test measurements on a commercial Si single-crystal wafer were performed to demonstrate that the method is sufficiently accurate.     

Characterization of simple and reproducible vascular stenosis model in hypercholesterolemic hamsters

The importance of low-density lipoprotein (LDL) in the etiology of atherosclerosis is well recognized. We have established a reproducible stenosis model in hypercholesterolemic hamsters, and the process of arterial stenosis by thrombus or neointima was studied and compared with that in normal hamsters. The level of plasma LDL was 4.6 times higher in hamsters fed a high-cholesterol diet than in hamsters fed normal food. Endothelial injury in right common carotid arteries was induced using a modified catheter. Arterial blood flow was monitored continuously using a Doppler flow probe. Arterial patency after the initiation of injury in high-cholesterol hamsters was significantly changed as compared with that of normal hamsters. Neointima was observed 2 wk after the vascular injury. The neointimal area of high-cholesterol hamsters was significantly larger than that of normal hamsters. To characterize the stenosis in hypercholesterolemic hamsters, we measured platelet aggregation, thrombin time, activated partial thromboplastin time, and proliferating smooth muscle cells (SMC) in vitro and in vivo. The half-maximal inhibitory concentration value for platelet aggregation induced by thrombin or collagen, the DNA synthesis stimulated by plateletderived growth factor (PDGF)-BB, and 5-bromo-2-deoxy-uridine labeling indices (proliferating index of SMC in vivo) in high-cholesterol hamsters were each significantly higher than the comparable value from normal hamsters. However, specific binding of PDGF-BB in SMC was not different between the two types of hamsters. Furthermore, we investigated the inhibitory effects of probucol or losartan on neointima formation using this model. Probucol, but not losartan, significantly reduced the neointimal area in hypercholesterolemic hamsters. These findings indicated that high levels of plasma LDL strongly contributed to the development of thrombus and neointima formation via both up-regulation of platelet aggregation and the enhancement of SMC proliferation. This stenosis model may be useful for the investigation of hypercholesterolemia-associated cardiovascular diseases.     

Integrated optical digital-to-analogue converter and itsapplication to pulse pattern recognition

An optical digital-to-analogue converter that enables optical pulse pattern recognition, fabricated on the silica-based planar lightwave circuit, is proposed. The converter features an optical transversal filter with a multimode interference combiner. Various kinds of four-bit pulse patterns at 10 Gbit/s have been successfully recognised with the fabricated converter     

Characterization of cellulose microbeads prepared by a viscose‐phase‐separation method and their chemical modification with acid anhydride

Chemically modified cellulose microbeads are useful as cosmetic materials. Cellulose microbeads as supports, prepared by a viscose‐phase‐separation method, are monodisperse and spherical. However, cellulose shows only slight hydrophilicity, even though it has three hydroxyl groups per pyranose ring, because cellulose possesses high crystallinity on account of the cellulose II structure derived from hydrogen bonds among the hydroxyl groups. To increase the hygroscopicity of cellulose microbeads, we have carboxylated them with succinic and glutaric anhydrides. Their hygroscopicity increases with the addition of succinoyl and glutaroyl groups. Moreover, we have confirmed the increased hygroscopicity of microbeads with sodium salinization. We have investigated the decomposition of these hydrophilic cellulose microbeads in aqueous buffer solutions and have confirmed that succinoylated cellulose is more readily decomposed than glutaroylated cellulose microbeads in aqueous solutions. On the other hand, to increase the lipophilicity of cellulose microbeads, we have acylated them with acetic and hexanoic anhydrides. Hydrophobizing microbeads with hexanoyl groups provides an affinity to benzene but not to H₂O. In contrast, hydrophobizing with acetyl groups provides affinity not only to benzene but also to H₂O. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 149–157, 2005     

On-line Test for Train Communication Based System

This paper gives out a new train automatic control system, which is based on train communication, and proposes a high assurance method to construct the system from current system. In current automatic train control (ATC) system, the central logic device detects position of each train and calculates permissible speed of each blocking section. Therefore, the central logic device controls speed of all trains. On the contrary, in the new system proposed in this paper, there is no central logical device and, train can communicate each other. The train detects the position and calculates the permissible speed itself according to the received position information of the preceding train. In the traditional method of changing an old system to a new one, test must be done off-line.While the integration technique proposed in this paper achieves on-line properties, and high assurance can be satisfied.     

Variable group-delay dispersion equalizer using lattice-formprogrammable optical filter on planar lightwave circuit

The authors report, in detail, an integrated-optic variable group-delay dispersion equalizer based on a lattice-form programmable optical filter. The variable dispersion equalizer consists of an alternating cascade of symmetrical and asymmetrical Mach-Zehnder interferometers. An equalizer with nine symmetrical and eight asymmetrical interferometers is fabricated on a planar lightwave circuit and its dispersion varied step by step from -681 to +786 ps/nm in the operational frequency range of 16.3 GHz. The effectiveness of the equalizer is shown by compensating the dispersion of three different fibers with a single equalizer. The performance of the equalizer is also evaluated and examined by numerical investigations