Topology optimization for worst load conditions based on the eigenvalue analysis of an aggregated linear system

This paper proposes a topology optimization for a linear elasticity design problem subjected to an uncertain load. The design problem is formulated to minimize a robust compliance that is defined as the maximum compliance induced by the worst load case of an uncertain load set. Since the robust compliance can be formulated as the scalar product of the uncertain input load and output displacement vectors, the idea of “aggregation” used in the field of control is introduced to assess the value of the robust compliance. The aggregation solution technique provides the direct relationship between the uncertain input load and output displacement, as a small linear system composed of these vectors and the reduced size of a symmetric matrix, in the context of a discretized linear elasticity problem, using the finite element method. Introducing the constraint that the Euclidean norm of the uncertain load set is fixed, the robust compliance minimization problem is formulated as the minimization of the maximum eigenvalue of the aggregated symmetric matrix according to the Rayleigh–Ritz theorem for symmetric matrices. Moreover, the worst load case is easily established as the eigenvector corresponding to the maximum eigenvalue of the matrix. The proposed structural optimization method is implemented using topology optimization and the method of moving asymptotes (MMA). The numerical examples provided illustrate mechanically reasonable structures and establish the worst load cases corresponding to these optimal structures.     

Remarks on the assignments of temperature programmed desorption peaks for the surface species formed on Cu/ZnO and ZnO in the methanol synthesis from CO

Temperature programmed desorption (TPD), IR spectroscopy and chemical trapping of the surface species with H₂O revealed that the TPD peak of CO frequently assigned to zinc formate species, which were formed in the course of the methanol synthesis from CO-H₂, arose from zinc methoxide species.     

Rational drug design and synthesis of a highly selective nonpeptide delta-opioid agonist, (4aS*,12aR*)-4a-(3-hydroxyphenyl)-2-methyl- 1,2,3,4,4a,5,12,12a-octahydropyrido[3,4-b]acridine (TAN-67)

We designed highly selective non-peptide agonists for the delta-opioid receptor. On the basis of the "message-address" concept in this field and the accessory site hypothesis, a novel class of heterocycle-fused octahydroisoquinoline derivatives were synthesized. One of these compounds [(4aS*,12aR*)-4a-(3-hydroxyphenyl)-2-methyl-1,2,3,4,4a,5,12, 12a -octahydropyrido[3,4-b]acridine, TAN-67 (2)] showed high selectivity for the delta-opioid receptor (Ki = 1.12 nM) in guinea-pig cerebrum with a 2070-fold lower affinity for the mu-opioid receptor and a 1600-fold lower affinity for the kappa-opioid receptor. TAN-67 was a potent delta-opioid receptor agonist with an IC50 value of 6.61 nM in the mouse vas deferens assay that was reversed by naltrindole (NTI) (Ke = 0.21). Moreover, TAN-67 was shown to have antinociceptive activity following subcutaneous administration in the mouse acetic acid abdominal constriction assay that was antagonized by NTI (delta 1- and delta 2-antagonist) and 7-benzylidinenaltrexone (delta 1-antagonist), but not by naltriben (delta 2-antagonist). This systemically applicable non-peptide agonist will be useful for elucidating the pharmacological properties of the delta-opioid receptor.     

Novel diagnosis of thermal deterioration for organic insulating resins by optical loss analysis

We propose an “optical loss analysis” as a novel nondestructive diagnosis for the thermal deterioration of insulating resins. Using an alkyd resin film, the optical absorptin loss per unit optical path length and the glass transition temperature (T_{g, DMA}) by dynamic mechanical analysis were measured during heating tests. At longer heating times, values of the optical absorption loss and the T_{g, DMA} increased concurrently. By rescaling the heating time as a reduced time as a reduced time, a master curve of the deterioration for the resin was obtained. Consequently, when thermal stress is the main cause of the deterioration, one can estimate the degree of deterioration and theoretically the residual lives of resins using this optical loss analysis.     

The state of adsorbed oxygen species formed in the decomposition of N2O on CaO

Temperature programmed desorption, FT-IR spectra and hydrolysis of adsorbed oxygen species revealed that a considerable amount of adsorbed peroxide species were formed on CaO by decomposition of N₂O, whereas no adsorbed species were formed by molecular oxygen.     

Study of high thermal conductive epoxy resins containing controlled high‐order structures

Heat is transported by phonons through dielectric solids such as ceramics and organic insulating resins. Especially in organic insulating resins, phonons scatter intensely mainly by their amorphous structure, which affects their thermal conductivities, usually 1 to 3 orders lower than those of ceramics and metals. Here, we show that by the thermosetting resin system with a crystal‐like structure that is microscopic anisotropy, the thermal conductivities of the resin themselves can be improved while keeping their macroscopic isotropy. We studied four kinds of diepoxy monomers with a biphenyl group or two phenyl benzoate groups as mesogens, and cured them thermally with an aromatic diamine curing agent. These thermal conductivities were maximally 5 times higher than that of conventional epoxy resins because mesogens were highly ordered to form crystal‐like structures to suppress phonon scattering. We also succeeded in the direct confirmation of the existence of crystal‐like structures in the epoxy resins by TEM observation. These results suggest a novel strategy to improve thermal conductivities of insulating resins themselves by controlling the high‐order structures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2464–2467, 2003     

Nondestructive diagnosis of thermal aging for opaque epoxy resin by optical reflective analysis

A novel nondestructive diagnosis using optical reflective analysis is proposed to evaluate thermally aged opaque insulating resins. Values of reflective absorbance (A_R) in the visible to near infrared (IR) range were measured under a variety of aging conditions using the bisphenol-A type epoxy resin tapes containing iron oxide pigment. The A_R values increased markedly over 180°C before and after heating. This increase was due to the electronic transition absorption caused by thermal oxidation of the resin. By rescaling the aging time as a reduced time, a master curve to evaluate thermal aging of the resin was obtained. Furthermore, a similar curve was obtained using the difference (ΔA_R) of the A_R values between two wavelengths in the near IR range. This indicated that the surface reflectivity dependence on raggedness and dust and stain could be reduced. Consequently, when the thermal stress was the main cause of aging, the aging and residual life of the resin could be evaluated using this method.     

Delamination mechanism of high‐voltage coil insulators made from mica flakes and thermosetting epoxy resin

To clarify the delamination mechanism of high‐voltage coil insulators made from mica flakes and epoxy resin due to static mechanical stress, the relationships between the shear strength of the insulator and the physical properties of the component materials were studied. The mechanism of their delamination was thought to be either a lack of epoxy resin between the mica flakes, interface failure between the mica flakes and the epoxy resin, or cleavage of the mica flakes. The first two mechanisms were discounted because the shear strength of the insulator was found to be independent of both the contact angle of the corresponding liquid epoxy resin on the mica flakes and the critical surface tension of the epoxy resin. Furthermore, the shear strength of the model insulator was improved by using an epoxy resin with a higher bending elastic modulus, implying that the delamination mechanism in this system is the cleavage of mica flakes. Therefore, the epoxy resin should have a high elastic modulus to ensure high delamination resistance, that is, the temperature to which the insulators are exposed should be lower than the glass transition temperature of the corresponding epoxy resin. Optical microscope studies also supported these results. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2164–2169, 2001     

Temperature programmed oxidation of Cu/ZnO catalysts with N2O: an attempt for characterization of copper catalysts

For characterization of the surface structure of metallic copper formed on the support, temperature programmed oxidation (TPO) with N₂O was carried out over various Cu/ZnO catalysts. Four peaks of the N₂ formation (, , and ) were observed at 223, 400, 545 and 600 K in the TPO runs. The average copper crystallite size estimated from the sum of the amount of - and -peaks agreed fairly with those determined by X-ray diffraction and transmission electron microscopy. It was concluded that - and -peaks resulted from the oxidation of metallic copper atoms on the steps, corners and/ or defect sites, and on the flat sites of the surface of copper crystallites, respectively, while - and -peaks resulted from the bulk oxidation of copper.     

Difference in the reactivity of acetaldehyde intermediates in the dehydrogenation of ethanol over supported Pd catalysts

Catalytic performances of supported Pd catalysts for the dehydrogenation of ethanol were greatly modified upon the formation of Pd alloy phases. Over Pd–Zn, Pd–Ga and Pd–In alloys, acetaldehyde was selectively produced at lower conversion levels. With the increased conversion level, ethyl acetate was produced at the expense of acetaldehyde. The selectivities for the ethyl acetate formation exceeded that over a Cu/ZnO catalyst. Over metallic Pd, the decomposition of ethanol, C₂H₅OH → CO + CH₄ + H₂, occurred to a considerable extent. It was shown that the reactivity of acetaldehyde species over the Pd alloys was markedly different from that over metallic Pd. Over the Pd alloys, acetaldehyde species were stabilized and transformed into ethyl acetate by the nucleophilic addition of ethanol. By contrast, over metallic Pd, aldehyde species were rapidly decarbonylated to methane and carbon monoxide. This revised version was published online in July 2006 with corrections to the Cover Date.