Dynamic Soil Stiffnesses at Side of Embedded Structures with Rectangular Base

Soil behavior at the side of an embedded structure with rectangular base area is formulated. The soil medium is idealized as a stack of horizontal sheets interconnected by distributed vertical springs. Each sheet is made of a previously proposed column-spring system. The computed results indicate that, at frequencies higher than the fundamental natural frequency of the soil medium, the vertical springs can be eliminated and each sheet can be treated as an independent sheet in the plane strain condition. This approximation and Galerkin’s method for weighted residuals lead to very simple expressions for the soil stiffnesses per depth at the side of a structure with rectangular cross section. The formulations developed are computationally very convenient and confirmed to produce results close to those computed by a far more rigorous method. The dynamic soil stiffnesses at the side of a structure are computed for various cases. The dynamic response analyses of partially embedded structures are presented to demonstrate the application of the approach and formulations developed.     

Electrical properties of a cyclotriphosphazene matrix polymer: Cyclotri(trifluoroethoxy, acryloyloxy-ethyleneoxy)phosphazene matrix polymer

Cyclotri(trifluoroethoxy, acryloyloxy-ethyleneoxy)phosphazene compound is synthesized from the cyclic trimer of dichlorophosphazene by replacing two CI atoms with trifluoroethoxy and acryloyloxy-ethyleneoxy groups. This compound was polymerized by UV irradiation with the aid of a photosensitizer. The polymerization proceeds in the acrylate group by opening the double bond. Whereas the matrix polymer is an insulator at low temperatures, it is a semiconductor at high temperatures. Namely, the conductivity is 8.84×10^–9 S/cm at 19.2°C and 1.17×10^–6 S/cm at 75.0°C. Both dielectric constant and dielectric loss increase with increasing temperature and with decreasing frequency. The conductivity of the cyclotri(trifluoroethoxy, acryloyloxy-ethyleneoxy) phosphazene monomer is higher than that of the corresponding polymer and the dielectric constants are higher at lower frequencies. These results are consistent with the existence of a charge transfer complex.     

Ultrastructural organization of the transverse tubules and the sarcoplasmic reticulum in a fish sound-producing muscle

The ultrastructural basis for the extremely rapid contraction-relaxation cycle (up to 300 s(-1)) in the swim-bladder muscle (SBM) of a scorpionfish (Sebastiscus marmoratus), producing characteristic sounds for communication, was investigated by electron microscopy. The SBM fibres contained well-developed sarcoplasmic reticulum (SR) showing triadic contacts with well-organized transverse tubules (T tubules). It was newly found that different types of triadic contacts were present within the single SBM fibre. In the middle region of the fibre (approximately 54% of the fibre length), the triadic contacts were located around the level of boundary between the A- and I-bands (AI-type triad). However in the two end regions of the fibre (approximately 21% and approximately 12% of the fibre length), the triadic contacts were seen around the level of the Z-band (Z-type triad). Between the middle and end regions of the fibre, T tubule-SR contacts exhibited the form of pentads composed of a pair of T tubules and three SR elements, and newly found heptads composed of three T tubules and four SR elements. The fractional volume of SR relative to the fibre volume was estimated to be approximately 26% in the middle region of the fibre with the AI-type triads and approximately 15% in the fibre ends with the Z-type triads. These results are discussed in connection with the mechanism, by which the mechanical activity of the SBM muscle is neurally controlled.     

A three-axis vibration isolation system using modified zero-power controller with parallel mechanism technique

This paper proposes a module-type three-degree-of-freedom vibration isolation system using modified zero-power control. Three vibration isolation modules are connected together using parallel mechanism to control 3-DOF motions. Each module consists of a common base, an individual middle mass and a common isolation table. The base to the middle mass is suspended by positive springs generated by active and passive system, and the middle mass and the isolation table is connected by negative spring realized by active-type modified zero-power control. The developed system could realize zero-compliance to direct disturbances as well as good ground vibration isolation. Furthermore, the isolation table is supported by a weight support mechanism for supporting heavy payloads. In the previous research, a concentrated middle mass with redundant actuators, in the vertical and horizontal directions, were used. Therefore, a vibration isolation system is proposed in this work using modular concept to overcome those drawbacks. Each module is controlled separately by decentralized control technique, and three modules can be used for three-degree-of-freedom of motion control. Therefore, no redundancy of actuator is occurred. Moreover, an improved zero-power controller is presented that can adjust negative stiffness instead of conventional zero-power controller. The results obtained from analytical and experimental studies show that the modular technique is reliable and efficient approach to vibration control, and represents a suitable alternative to the conventional active vibration isolation systems.     

Counterflow Quantum Turbulence and the Instability in Two-component Bose-Einstein Condensates

We theoretically study the nonlinear dynamics of the instability of counter-superflow in two miscible Bose-Einstein condensates. The condensates become unstable when the relative velocity exceeds a critical value, which is called counter-superflow instability. We reveal that the counter-superflow instability can lead to quantum turbulence by numerically solving the coupled Gross-Pitaevskii equations. The modes amplified by the instability grow into solitons and decay into quantized vortices. Eventually, the vortices become tangled and quantum turbulence of two superfluids. We show that this process may occur in experiments by investigating the dynamics in a 2D trapped system.     

Reinvestigation of the Solidification Point of CaO by Digital Pyrometry

The solidification point of calcia which has been distributed by the Commission on High-Temperature and Solid-State Chemistry of the International Union of Pure and Applied Chemistry was measured by digital pyrometry using an arc imaging furnace. The solidification point was determined to be 2899°C with ±3°C as the standard deviation for this sample. The reliability of this solidification point was determined to be within ±17°C based upon discussions of the measuring system and the material.     

Behavior of Ca(OH)2/CaO pellet under dehydration and hydration

With construction of a thermochemical energy conversion prototype system to store solar heat, thermal dissociation of pellets of Ca(OH)₂ and hydration of CaO have been investigated in some detail for its application to the system. The inorganic substance is very attractive as a material for long term heat storage, but molar density changes associated with the reaction are fairly large. Therefore, this factor has been taken into account in the kinetic equation. The importance of additives and pellet size has been discussed considering reactivity and strength of pellets. An analysis has been attempted when chemical reaction is important. The deformation of pellets was observed during hydration.     

High output-power and narrow spectral-linewidth operation of a1.3-μm gain-coupled DFB laser with InAsP buried absorptive grating

High output-power and narrow spectral-linewidth operation of 1.3-μm gain-coupled distributed feedback lasers with grating are reported. The fabricated output power of 230 mW and a linewidth of 100 kHz by reducing optical confinement in multiple quantum wells to improve the single-mode stability at high output-power operation