Fail Safe Research Articles

Sustainable Earthquake-Resistant Mixed Multiple Seismic Systems

Mixed multiple seismic systems (MMSSs) are ideally suited for sustainable seismic design (SSD). MMSSs are combinations of two or more different earthquake-resisting structures (ERSs) that provide lateral support for gravity frameworks. Same-system combinations have been demonstrated to not be suitable for SSD. Regardless of the carbon footprint reduction, unless a structure has been designed for seismic sustainability it would be disposable with greater harm to the environment. Here, design means planning for both seismic resistance as well as post-earthquake realignment and repair (PERR). Earthquakes are random, natural, and dynamic events, whereas PERR is a deliberate, manual, and static process. In SSD the practicality of PERR is as important as the relevance of the theoretical assumptions. In SSD the non-lateral-resisting items are designed not to partake in seismic resistance, nor hinder the realignment process. Additionally, efforts are made to mitigate the P-delta effects that undermine the global strength of the system and oppose the recentering effort. The purpose of this paper is to identify and remedy design flaws and physical issues that prevent MMSSs from achieving seismic sustainability as cost-effectively as possible. Two newly developed technologies, the ladder moment frame (LMF), and the fail-safe (FS) system, as well as a capacity distribution rule together with six simple axioms are introduced. Brief descriptions of LMF and FS are presented in the text.

Assessment of a seismic tuned mass damper with friction fail‐safe mechanism for the vibration control of high‐rise buildings

This study proposes a method for mounting a tuned mass damper (TMD) at the top of a high-rise building through a fail-safe (FS) mechanism using a friction device to protect against strong earthquakes, such as those with long-period, long-duration ground motions. The control effect by the TMD with the proposed friction FS mechanism in single-degree-of-freedom and 30-degrees-of-freedom (30DOF) building models was numerically investigated by an earthquake response simulation. Also, the response for the same building models with TMDs incorporating different FS mechanisms (a bilinear viscous type and a displacement-dependent hardening type), TMDs with no FS mechanism, and no seismic protection (uncontrolled case) was examined for comparison. The obtained results demonstrated that use of the proposed friction FS mechanism prevents the TMD from operating beyond its design displacement limit; thus, this system avoids damage due to the TMD falling or colliding. Moreover, the proposed friction FS mechanism generally showed the most promising control effects among all 30DOF building models with TMD incorporating FS mechanism regarding the peak response of the TMD displacement and the building roof acceleration and displacement.

Upsizing high-strength fail-safe steel through warm tempforming

Fail-safe (FS) steel is designed with enhanced fracture toughness through the crack deflection mechanism in an anisotropic microstructure. In this study, commercial boron (B)-bearing medium-carbon low-alloy steel bars with a cross-sectional area of 1390 mm2 were water-quenched and tempered at temperatures between 400 °C and 500 °C, followed by multi-pass caliber-rolling (i.e., warm tempforming). Tensile, Charpy V-notch (CVN) impact, and hydrogen embrittlement (HE) properties of the warm tempformed samples were investigated and compared with the rolling reductions of 45–92% to optimize the rolling conditions for upsizing the FS steel. Warm tempforming at 400 °C with a rolling reduction of 66% successfully produced an FS steel bar with a large cross-sectional area of 470 mm2. The evolution of a heterogeneous and anisotropic ultrafine-grained structure through the warm deformation of tempered martensite and pearlite generated an excellent combination of CVN toughness and HE resistance at the ultimate tensile strength of 1400 MPa. Delayed fracture resistance of the FS steels was also evaluated to be far superior to those of conventionally quenched and tempered steels, based on the balance between the HE susceptibility and hydrogen entry. Furthermore, it was observed that excessive warm tempforming to a rolling reduction of 92% tended to degrade the tensile elongation and HE resistance. The mechanism of the variations in mechanical properties during warm tempforming is discussed in association with the microstructural evolution.

Developing safe and immune-tolerated cells for treatment of neurological diseases

Background & Aim Cell therapy-based regenerative medicine provides a powerful tool against diseases that have been intractable to treat with conventional medicine. Employing genome-editing strategies, we addressed the safety concerns associated with cell-based regenerative medicine through the development of the FailSafe (FS) Cell System. This proprietary technology inserts a suicide gene into a cell division essential locus, allowing selective elimination of proliferative cells through the administration of a pro-drug, whilst also protecting the suicide gene from inactivation. When incorporated into mouse embryonic stem cells (mESCs) and injected subcutaneously, the Fail-Safe system allows the proliferating component of a teratoma to be eliminated by brief treatment with the pro-drug for the suicide gene. The remaining non-proliferating component is induced into a stable and dormant ectopic tissue. To enable the development of economically feasible “off-the-shelf” cell products, we identified a set of eight immune-modulating genes involved in allograft tolerance and rejection. When expressed in FailSafe mESCs, the immune-cloaking system is sufficient to prevent rejection of ectopic tissues in immune-competent major histocompatibility complex-mismatched recipient mice. In the current study we sought to demonstrate the application of our technology for treatment of neurological diseases. Methods, Results & Conclusion By incorporating expression of enhanced firefly luciferase, we used bioluminescence imaging (BLI) to monitor the survival and proliferation of gene-edited mESCs after stereotaxic injection into the mouse brain. Small numbers (1 × 104) of mESCs injected into the lateral ventricles were detectable by BLI. Weekly monitoring of live animals revealed that the BL signal increased over time, indicative of the proliferation of injected cells. Histological examination of brain tissue confirmed that mESCs formed teratomas containing structures derived from the three primary germ layers. In mice that received gene-edited mESCs, teratoma development could be prevented by intraperitoneal administration of the pro-drug. Moreover, proliferating cells could be eliminated from developing teratomas, as shown by a decreased BL signal over time and Ki67 staining in tissue sections. Importantly, grafted cells that had undergone terminal differentiation remained intact. These technologies will therefore facilitate the advancement of cell-based regenerative therapies for neurological diseases.

Probabilistic Analysis of Alarm Subsystems with Different Types of Human Interface and Safety-Control Policies

This paper gives four types of alarm subsystem configurations which include fault-alerting and safety-presentation types, where two.kinds of correspondence between sensor states and plant states are distinguished. For each configuration, we give a probabilistic analysis on fail-safe (FS) failures and fail-dangerous (FD) failures. We prove that we can have an optimal alarm subsystem which minimizes FS and FD failures probabilities simultaneously by choosing a human-machine interface configuration and an associated safety-control policy in an appropriate manner.

Reliability measures for fail safe computer-based systems

Two types of fail-safe (FS) computer-based systems, i.e. FS-stop computer-based systems and FS-active computer-based systems are dicussed. Some important reliability measures for these computer-based systems are introduced.

MTBRD analysis of fail-safe systems

In this paper, on the basis of a general model, an important index of fail-safe (FS) systems—MTBRD (mean time between system recovery from a dangerous-side failed status and the next dangerous failure)—is to be defined, and the effect of changing Q—the kernel of the semi-Markov process which describes the status of an FS system—on MTBRD are evaluated. From these analytical results, three measures for weighing the effectiveness of an FS technique can be defined, by which the system designers are able to quantitatively analyze the effects of the adopted FS techniques on safe operation.

Unified Design of Self-Checking and Fail-Safe Combinational Circuits and Sequential Machines

This correspondence deals with a unification and extension of some previous work on self-checking (SC) and fail-safe (FS) systems.