Vertical Seismic Isolation Device for Three-Dimensional Seismic Isolation of Nuclear Power Plant Equipment—Case Study

The purpose of this study was to develop a vertical seismic isolation device essential for the three-dimensional seismic isolation design of nuclear power plant equipment. The vertical seismic isolation device in this study has a concept that can be integrally combined with a conventional laminated rubber bearing, a horizontal seismic isolator with a design vertical load of 10 kN. To develop the vertical seismic isolation device, the vertical spring and the seismic energy dissipation device capable of limiting the vertical displacement of the spring were designed and their performances were verified through actual tests. In this study, the target elevation of the floor is 136 ft, where safety-related nuclear equipment, such as cabinet and remote shutdown console, etc., is installed. The sensitivity studies were carried out to investigate the optimal design vertical isolation frequencies for the target building elevation. Based on the results of the sensitivity study, a disc spring and a helical coil spring were selected for the vertical stiffness design, and the steel damper was selected for the seismic energy dissipation, and their performance characteristics were tested to confirm the design performance. For the steel damper, three types were designed and their energy dissipation characteristics by hysteretic behavior were confirmed by the inelastic finite element analyses and the tests in static fully reversed cyclic conditions. Through the study of the vertical seismic isolation device, it was found that 2.5 Hz~3.0 Hz is appropriate for the optimal design vertical isolation. With results of the vertical seismic isolation performance analysis, the appropriate number of steel dampers are proposed to limit the vertical seismic displacement of the spring within the static displacement range by the design vertical load.

Design, Manufacturing, and Performance Evaluation of a Novel Smart Roller Bearing Equipped with Shape Memory Alloy Wires

In this study, a new type of seismic isolation device, called SMA wire-based roller bearing (SMA-RB) is developed and introduced. The SMA-RB has been designed, manufactured, and experimentally tested. This bearing consists of cylindrical roller bearings and SMA wires with straight or cross configurations, as supplementary damping elements. In such a smart bearing, the superelastic SMA wires are passed through the hooks/pulleys attached to the supporting plates of the bearings in different configurations. The rollers provide lateral flexibility, and SMA wires supply energy dissipation and self-centering properties. In the manufacturing stage, a new mechanism for coupling wires (i.e. SMA wire joiner/coupler) is proposed. The results show that SMA wires, made of Nickle Titanium (NiTi), provide a self-centered damping mechanism with almost zero residual deformation which can effectively control the device from over-displacement. While using pulleys and newly designed wire joiners in the SMA-RB, the bearing can experience a stable cyclic behavior. Since the rollers generate a negligible amount of frictional force, the superelastic NiTi wires with a flag-shaped hysteresis mainly contribute to the overall shear hysteretic response of the SMA-RB. A triangular-shaped constitutive model can be used to accurately describe the hysteretic behavior of SMA-RB with different wire configurations.

Development and Successful Field Trial of Retrievable, Instrumented & Tandem Downhole Isolation Valve RIT-DIV System

This paper describes the development and field deployment of a new downhole isolation valve system called the Retrievable, Instrumented & Tandem Downhole Deployment Valve (RIT-DDV). The purpose of this technology is to provide a temporary mechanical barrier to isolate and monitor the well during drilling operations in an environment where a full column of single-phase fluid cannot be maintained. The RIT-DDV is based on predominantly used downhole isolation valve (DIV) design and technology, which is a hydraulic flapper-type isolation device installed in the casing that seals the open hole during pipe tripping operations. The key features of the new RIT-DDV systems are dual flapper valves with three downhole pressure and temperature gauges to take measurements above, between, and below the flappers. The advantage of this configuration is that it enhances safety by enabling double-block-and-bleed system functionality, providing valve redundancy, and moreover allowing for continuous real-time monitoring of downhole well conditions. In addition, the RIT-DDV is designed to be reusable and can be tested upon installation and replaced if necessary. The RIT-DDV system enabled the operator to isolate and monitor the well while drilling through a depleted formation that prevented drilling with a full column of single-phase drilling fluid. The RIT-DDV was successfully trialed in western Kazakhstan and demonstrated the potential of this technology to enhance the safety of drilling heavily fractured carbonate formations with reservoir fluids containing hydrogen sulfide (H2S) / carbon dioxide (CO2) that are prone to total loss of circulation. The downhole pressure / temperature monitoring capabilities that the system provides within the casing string helped drill through the depleted fractured carbonate reservoir section without incurring non-productive time (NPT).

Probabilistic methods for calculating seismic resistance of buildings

The article aims to assess possibilities of using probabilistic methods for calculating seismic resistan of buildings based on the laws of structural mechanics. The design schemes and models of buildings rigidly embedded in the base and with a seismic isolation device are described. Formulas developed on the basis of the law of energy conservation, namely the seismodynamic law, which allow to estimate the coefficient of dynamism, are presented. It is proposed to abandon the main modes of vibration in the calculations, i.e. the coefficient ηir of the waveform and the vibration frequency of the residential building and the foundation during earthquakes. Shear and bending calculations of a residential building are based on the design model developed. The values of seismic force are determined by the first and last modes of vibration. Based on these values, it is proposed to calculate internal forces and deformations in the bearing structures of buildings using the methods of structural mechanics.

Compact Galvanically Isolated Architectures for Low-Power DC-DC Converters with Data Transmission

This paper reviews state-of-the-art architectures for galvanically isolated DC–DC converters with data transmission for low-power applications. Such applications do not have stringent requirements, in terms of power efficiency, but ask for very compact, highly integrated implementations. To this aim, architecture simplicity is crucial, especially when data transmission and/or output power regulation are required. Since the bottleneck of galvanically isolated systems is the isolation device (i.e., typically a stacked thick oxide or polyimide transformer), the reduction of the number of isolated links, while preserving both power and data functionalities, is the more effective strategy to increase the level of integration, reduce the form factor, and have a lower cost per channel. Specifically, this review compares the pros and cons of different architectures that address this challenge differently from traditional solutions.

1431 Stoma Intubation, Isolation and Negative Pressure Wound Therapy for Complex Stoma-Associated Wounds: New Technique and Case Series

Background The use of negative pressure wound therapy (NPWT) in colorectal surgery has been demonstrated for treating perineal defects, enterocutaneous fistula and stoma dehiscence. Here we describe a technique for closure of complex stoma-associated wounds using a novel commercial intubation device alongside NPWT to protect the surrounding wound from the stoma effluent. The device has previously described for use with enterocutaneous fistula. We present two cases that have been successfully treated with this technique. Technique and Cases The first case is of 88-year-old women with a retracted loop ileostomy and the second a 48 year-old male with a retracted end colostomy. Both patients underwent significant emergency peristomal debridement and in both cases the commercial device was deployed to intubate the stoma. VAC foam and standard adhesive dressings were used to form a quality seal and the pressure set to 125mmHg. In both cases near complete healing was achieved to the point that standard stoma bags and management could be used. Conclusions This is the first description of the use of an isolation device in complex stoma associated wounds. We have found the Fistula Funnel to be highly effective in this context.

Seismic Isolation Technology for Prestressed Segmental Precast Piers

Due to its poor energy dissipation capacity, the application of prestressed segmental precast piers in bridge engineering in areas with medium- and high-intensity seismic activity is limited. This study proposes the use of a functional separation seismic isolation device (FSID) that acts as an external replaceable energy dissipation device to increase the energy dissipation capacity of prestressed segmental precast piers. Full-scale in-situ load tests on an actual prestressed segmental precast pier were carried out to clarify the seismic performance of this kind of pier. Based on the results of the tests and further analysis, an optimal design of the functional separation seismic isolation device is obtained by incorporating the optimal mechanical performance parameters of the device. The FSID proposed in this study can meet the seismic performance requirements of prestressed segmental precast piers under different levels of earthquakes.