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.     

Design method for a new control system for an autonomous underwater vehicle using linear matrix inequalities

The independent administrative corporation Japan Agency for Marine–Earth Science and Technology (JAMSTEC) has developed a small light autonomous underwater vehicle (AUV) named marine robot experimental 1 (MR-X1).¹ The motion control of MR-X1 is considered in this article. Since the dynamics of MR-X1 mainly depends on its own speed, the motion control is a nonlinear control system. We propose a new controller design method for this system using linear matrix inequalities (LMIs). This algorithm gives a solution as a linear matrix inequality, and can be adapted to solve many LMIs simultaneously. LMIs can be obtained by substituting several speeds into the dynamics of the MR-X1. The proposed controller, which can be derived from the solution of the LMIs, was adapted to MR-X1 and showed good performance in experiments. This work was presented in part at the 11th International Symposium on Artificial Life and Robotics, Oita, Japan, January 23–25, 2006     

Tensile strength of composites with brittle reaction zones at interfaces

A theoretical model of the longitudinal strength of brittle fibre-reinforced composites with brittle reaction zones was presented for both cases of strongly and weakly bonded fibre/brittle zone interfaces. First, on the basis of the fracture mechanics, a model of the strength of the fibres coated with strongly adhering brittle zones was proposed as a function of the thickness of the brittle zones. Next, the conditions under which debonding occurs at the interfaces were investigated with the aid of the shear lag analysis proposed by Cox. The theoretical model was then examined using composites with strongly and weakly bonded interfaces. The proposed model agreed fairly well with the experimental results. Finally, the permissible thickness of the brittle zone below which no reduction in fibre strength appears was calculated, using the proposed theory, under the condition of strong interfacial bonding, for carbon, boron and silicon carbide fibres which are of practical use. The calculated values of the thickness were smaller than 1 m.     

Using intense plastic straining for high-strain-rate superplasticity

Ultrafine grain sizes may be introduced into bulk samples by using the intense plastic straining technique equal-channel angular pressing. This article describes the principles of equal-channel angular pressing and demonstrates the application of this procedure to attain ultrafine grain sizes in an Al-3Mg solid-solution alloy and a commercial cast Al-Mg-Li-Zr alloy. Provided there is stability of these ultrafine grains at elevated temperatures, as in the Al-Mg-Li-Zr alloy, equal-channel angular pressing may be used as a processing tool to achieve high-strain-rate superplasticity in materials that are not potentially superplastic. These results have important implications for reducing the long production times that are associated with the fabrication of complex parts using superplastic forming. Terence G. Langdon earned his Ph.D. in physical metallurgy at Imperial College, University of London, in 1965. He is currently professor of materials science and mechanical engineering at the University of Southern California, Los Angeles. Dr. Langdon is a member of TMS. Minoru Furukawa earned his D.Eng. in metallurgy at Kyushu University in 1988. He is currently an associate professor at Fukuoka University of Education, Munakata, Japan. Dr. Furukawa is also a member of TMS. Zenji Horita earned his Ph.D. in materials science at the University of Southern California in 1983. He is currently an associate professor of materials science and engineering at Kyushu University, Fukuoka, Japan. Dr. Horita is also a member of TMS. Minoru Nemoto earned his D.Eng. in materials science and engineering at Tohoku University in 1966. He is currently a professor of materials science and engineering at Kyushu University, Fukuoka, Japan. Dr. Nemoto is also a member of TMS.     

An optical fiber flow speed sensor of increased sensitivity

A simple-structured speed sensor in which a polarization-maintaining optical fiber is used as a Karman vortex generator and also as a vortex frequency sensor had earlier been proposed. For measuring ocean current velocity, a double-fin-type sensor mount was designed and investigated in detail experimentally. Although the experimental results showed its essential effectiveness, several problems were found. A conduit-type sensor mount has newly been proposed for solving these problems. A sensor for this mount has been constructed by using a circular pipe 16 mm in diameter. Experimental studies of the sensor show a wide range of agreement between detected frequencies versus measured flow speeds and the frequencies expected from the Roshko equation. The minimum detectable flow speed is 0.27 m/s. © 1998 Scripta Technica, Electr Eng Jpn, 125(1): 1–8, 1998     

DISLOCATION PINNING IN HIGH TEMPERATURE DEFORMED Ni3(Al,Ti) SINGLE CRYSTALS CONTAINING DISORDERED γ PRECIPITATES

A transmission electron microscopy (TEM) investigation has been performed on the dislocation pinning in LI2-ordered Ni3(Al, Ti) containing disordered γ precipitates. The morphology of deformation induced dislocations in the γ' base alloys containing fine dispersion of disordered γ was investigated by means of weak-beam electron microscopy. The superdislocations are strongly attracted to the disordered particles and dissociate on the (111) plane in the γ particles, while they dissociate on the (010) plane in the γ' matrix. The disordered γ precipitates play an important role as a pinning point during the cross-slip of superdislocations from (111) to (010) planes in the γ'matrix and restrain the cross-slip of superdislocations. The interaction of superdislocations with disordered particles causes the formation of superkinks, jogs and closed loops.     

A COUNTER CURRENT EXPERIMENT FOR THE SEPARATION OF TRIVALENT ACTINIDES AND LANTHANIDES BY THE SETFICS PROCESS

ABSTRACT

The SETFICS process, a variation of TRUEX process, was developed for the recovery of Am and Cm from acidic waste solution and the separation of actinides (III) and light lanthanides. The process uses the general TRUEX solvent as the extracting reagent and a DTPA-sodium nitrate solution for selective stripping of actinides(III). The basic flow sheet is composed of four steps: extraction-scrubbing; acid stripping; actinide(III) stripping; and lanthanide stripping.

To demonstrate the usefulness of the SETFICS process, a counter current experiment was conducted using a real TRUEX product solution. Americium and curium were successfully recovered with a solution of 0.05 M DTPA-4 M NaNO₃ (pH 2.0). Although the actinide(III) product solution contained Sm and Eu, the decontamination factor of ¹⁴⁴Ce/²⁴¹Am was 72, and most of the light lanthanides, specifically La, Ce, Pr, Nd, were removed. At least 80 % of the lanthanides were separated from the Am and Cm end products. In order to minimize the acidity in the actinide(III) stripping step, the nitric acid which extracted with the trivalent metals was previously removed with a solution of 0.5 M NaNO₃ (pH 2.0) in the “acid stripping” step.     

Nanoscale Cellular Foams from a Poly(propylene)‐Rubber Blend

Plastic foams with nano/micro‐scale cellular structures were prepared from poly(propylene)/thermoplastic polystyrene elastomer (PP/TPS) systems, specifically the copolymer blends PP/hydrogenated polystyrene‐block‐polybutadiene‐block‐polystyrene rubber and PP/hydrogenated polystyrene‐block‐polyisoprene‐block‐polystyrene. These PP/TPS systems have the unique characteristic that the elastomer domain can be highly dispersed and oriented in the machine direction by changing the draw‐down ratio in the extrusion process. A temperature‐quench batch physical foaming method was used to foam these two systems with CO₂. The cell size and location were highly controlled in the dispersed elastomer domains by exploiting the differences in CO₂ solubility, diffusivity, and viscoelasticity between the elastomer domains and the PP matrix. The average cell diameter of the PP/TPS blend foams was controlled to be 200–400 nm on the finest level by manipulating the PP/rubber ratio, the draw‐down ratio of extrusion and the foaming temperature. Furthermore, the cellular structure could be highly oriented in one direction by using the highly‐oriented elastomer domains in the polymer blend morphology as a template for foaming.