Numerical study on post-fracture redundancy of the two-girder steel-concrete composite highway bridges

As the Japan bridge inventory ages and traffic volumes increase, the government is spending more on maintaining their existing structures to extend the service life of the current bridge inventory. This includes two-girder bridges that are classified as fracture critical and non-redundant. Owing to the increased inspection costs associated with these fracture-critical bridges, there is a need to evaluate alternate load paths and to implement retrofit methods on existing bridge structures to avoid bridge replacement. In this paper, fracture redundancy of the two-girder bridge is investigated through a case study for a three-span continuous twin I-girder bridge. The finite element analysis is carried out to evaluate the load-carrying capacity after fracture of a girder of the two-girder bridge. Damage of studs near the moment contra-flexure regions are also considered in this study. Spacing between the transverse beams is discussed as possible techniques to improve redundancy and reduce the fracture potential of two-girder bridge structures. The concrete slab is indicated to be a significant member for guarantying the redundancy of the two-girder steel-concrete composite bridges.     

A study on the deterioration characteristics of power capacitors with oil-impregnated paper

Power capacitors are highly reliable due to their completely enclosed configuration. They are relatively trouble-free over the long term. However, their dielectric strength can be reduced due to some stresses, including overvoltage application or thermal degradation of the insulation material during long periods of operation; these events can result in dielectric breakdown of capacitors in extreme cases. Since almost all power capacitors with oil-impregnated paper have been operated for more than twenty years, some kind of failure should be expected. To prevent these incipient accidents, it is important to examine the insulation deterioration mechanism and evaluate the degree of deterioration before capacitor breakdown. To establish a diagnostic method of deterioration of the capacitors with oil-impregnated paper, we have conducted thermally and electrically accelerated deterioration tests and investigated the changes of their characteristics. Based on the experimental results we obtained, it can be concluded that the behavior of the oil-dissolved gases can be used as a useful index to diagnose the insulation deterioration of these capacitors.     

Effect of molecular weight distribution of poly(oxytetramethylene)glycol on cut growth resistance of polyurethane

A new method is proposed to improve the cut growth resistance of polyether-based polyurethane elastomers, i.e., polyethers used in this method are characterized by a double-humped distribution of molecular weight (DHDM), prepared by blending low-molecular-weight components and high-molecular-weight ones. The measurements of stress–strain curves, viscoelastic properties, and DSC thermograms of polyurethane elastomers before and after fatigue tests indicate that the destruction of the super molecular structure because of fatigue is smaller in the elastomer by our method, while in the conventional elastomer it is greatly destructed to change into fibrous structure. Further, the broad line NMR measurements show that the molecular motion of DHDM-type elastomers is more active, which is considered to contribute to the improved cut growth resistance of the elastomers.     

A post trip operational guidance system for BWR plants

A post trip operational guidance system (PTOG) for BWR power plants was developed to support the operators in achieving safe plant shutdown after a scram. The objective of PTOG is to support the operators in collecting plant information, in diagnosing plant status and in deciding corrective actions. To achieve this objective, PTOG has three main functions, i.e., the diagnosis of plant subsystems performance, the identification of safety functions status and the dynamic synthesis of operating procedures. The main advantage of PTOG is that it provides operating procedures irrespective of the transient's initiating event and evolutional history. The results of verification and validation tests showed that PTOG was a useful, effective and trustworthy vehicle in coping with abnormal plant conditions.     

Production of artistic images with “ART PROCESSOR”

“ART PROCESSOR” is a compact image processing system using a microprocessor. It can produce artistic pictures like oil painting from realistic pictures like photographs. We will present the image processing system and the algorithm to create artistic pictures in this paper.     

A study of rotor configuration for IPMSM with concentrated winding considering the iron loss

This paper reports an IPMSM rotor configuration with a concentrated‐winding stator. The inductance of the concentrated winding is greater than that of the distributed winding and the flux density of the concentrated winding contains higher harmonic components. The result is higher winding losses than in the IPMSM with a distributed‐winding stator. We discuss three types of interior magnetic rotor with different saliency ratios. In the lower speed range, the highest‐saliency rotor is effective in decreasing the load current and copper losses. On the other hand, in the higher speed range, the higher‐saliency rotors result in greater iron losses and lower motor efficiency; in this range, the lower‐saliency rotor is effective in decreasing iron losses and increasing motor efficiency. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(4): 71–78, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10005     

Possible explanations for trajectory curvature in multijoint arm movements.

Although the straightness of hand paths is a widely accepted feature of human multijoint reaching movement, detailed examinations have revealed slight curvatures in some regions of the workspace. This observation raises the question of whether planned trajectories are straight or curved. If they are straight, 3 possible factors can explain the observed curvatures: (a) imperfect control, (b) visual distortion, or (c) interaction between straight virtual trajectories and the dynamics of the arm. Participants instructed to generate straight movement paths produced movements much straighter than those generated spontaneously. Participants generated spontaneously curved trajectories in the frontoparallel plane, where visual distortion is not expected. Electromyograms suggested that participants generated straighter paths without an increase in arm stiffness. These findings argue against the 3 factors. It follows that planned trajectories are likely to be curved. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low-temperature synthesis of binary cuprates from hydroxide precursor

Binary cuprates of Sr₂CuO₃₊ and SrCuO₂ have been synthesized at low temperatures below 500 °C under various values of partial oxygen-pressure by thermal decomposition of hydroxide precursors, Sr₂Cu(OH)₆ and SrCu(OH)₄, respectively. The tetragonal Sr₂CuO₃₊ ( 0.3) is obtained by the heat-treatment at 400 ° C and 0.2 atm. The value of appears to be independent of and unchangeable. On the other hand, the orthorhombic Sr₂CuO₃₊ ( 0) is obtained by the heat-treatment at 400 °C in flowing gas of N₂. For 0 < < 0.2 atm, a mixture of the tetragonal and orthorhombic phases is obtained. The orthorhombic SrCuO₂ is obtained by the heat-treatment at 500 ° C in flowing gas of N₂, although the tetragonal SrCuO₂, namely, the so-called infinite-layer compound is not obtained.     

Analyzing soft tissue stiffness of human upper arms during physical dynamic and quasi-static impacts in human–machine interaction

Knowledge of the changes in the behavior of human soft tissue stiffness during physical impact in human–machine interaction (HMI) plays a vital role in the development of biofidelity testing devices such as a human dummy. These testing devices are widely applied as an effective means to validate the safety of machinery during dynamic or static contact with humans in HMI. In this study, we assess changes in soft tissue stiffness in the upper arm of individuals under both dynamic (0.7 and 0.25 m/s) and quasi-static (QS) impacts under a constrained contact condition. Three impactor shapes (cylindrical, cubic, and spherical) are used in this study. Impact experiments are conducted using impactors attached to a pendulum. The soft-tissue displacement is determined using an ultrasound device. The impact force-displacement curves illustrate the nonlinear behavior of the soft tissue stiffness under both dynamic and QS impacts. By utilizing the “Linear Mixed Model” statistical analysis, we found that changes in the impact velocity significantly influenced the changes in the nonlinear behavior of soft tissue stiffness while there was no significant effect of the changes in the impactor shape on the nonlinear behavior of the soft tissue stiffness. Additionally, we revealed that the changes in the soft tissue stiffness are influenced by the size of the contact area. Moreover, we demonstrated a range of changes in soft tissue stiffness for different impact velocities, which provide valuable information for developing future validation test devices in HMI, such as the design and evaluation of dummy skin.