Weakest Failure Research Articles

Failure Mode and Optimization for MSCSS with LRBs Based on IDA Method

The mega-sub controlled structure system with laminate rubber bearings is an emerging seismic control system for high-rise buildings. The system is high-order statically indeterminate with numerous failure modes. To study the failure modes of the structural system and further improve its seismic performance, the dynamic equations and the finite element model of the system were established. Ten different ground motions were selected from the Pacific Earthquake Engineering Research Center ground motion database for the incremental dynamic analysis (IDA). Based on the results of the IDA, the weakest failure mode of the system was identified, and its failure path was found. Two schemes were proposed to optimize the weakest failure mode of the system, and the optimization results were compared. The results show that although the IDA curves from different ground motion inputs are diverse, the plastic hinges are all formed on the sub-structures. Failures of the system are caused by either the excessive floor drift or the excessive shear deformation of rubber bearings. By adjusting the locations and parameters of dampers and rubber bearings, the seismic performance of the system can be improved.

Wait-freedom with advice

We motivate and propose a new way of thinking about failure detectors which allows us to define what it means to solve a distributed task wait-freeusing a failure detector. In our model, the system is composed of computation processes that obtain inputs and are supposed to produce outputs and synchronization processes that are subject to failures and can query a failure detector. Under the condition that correct (never failing) synchronization processes take sufficiently many steps, they provide the computation processes with enough advice to solve the given task wait-free: every computation process outputs in a finite number of its own steps, regardless of the behavior of other computation processes. Every task can thus be characterized by the weakest failure detector that allows for solving it, and we show that every such failure detector captures a form of set agreement. We then obtain a complete classification of tasks, including ones that evaded comprehensible characterization so far, such as renaming or weak symmetry breaking.

Implementing the weakest failure detector for solving the consensus problem

The concept of unreliable failure detector was introduced by Chandra and Toueg as a mechanism that provides information about process failures. This mechanism has been used to solve several agreement problems, such as the consensus problem. In this paper, algorithms that implement failure detectors in partially synchronous systems are presented. First two simple algorithms of the weakest class to solve the consensus problem, namely the Eventually Strong class (⋄S), are presented. While the first algorithm is wait-free, the second algorithm is f-resilient, where f is a known upper bound on the number of faulty processes. Both algorithms guarantee that, eventually, all the correct processes agree permanently on a common correct process, i.e. they also implement a failure detector of the class Omega (Ω). They are also shown to be optimal in terms of the number of communication links used forever. Additionally, a wait-free algorithm that implements a failure detector of the Eventually Perfect class (⋄P) is presented. This algorithm is shown to be optimal in terms of the number of bidirectional links used forever.

Risk-identification-based hybrid method for estimating the system reliability of existing jacket platforms under fire

This paper proposes a risk-identification-based hybrid method for estimating the system reliability of steel jacket structures under fire. The proposed method starts with risk identification; according to the results of hazard identification and Dow’s fire and explosion index (F&EI) methodology, the most dangerous hazard sources are determined. In term of each equipment layout in steel jacket structures, fire load is imposed and elasto-plastic analysis is performed. According to the deformed state of steel jacket structures, the weakest failure mode of steel jacket structures is identified. In order to know the effect on ultimate bearing capacity of the offshore structural system, a series of elasto-plastic analyses are performed in which single failure element contained in the weakest failure mode is removed from the whole offshore platform structural system. Finally, the failure function of the steel jacket structure is generated and the failure probability of the steel jacket structure system is estimated under fire by genetic algorithm via MATLAB program.

Renaming and the weakest family of failure detectors

We address the question of the weakest failure detector to circumvent the impossibility of $$(2n-2)$$ -renaming in a system of up to $$n$$ participating processes. We derive that in a restricted class of eventual failure detectors there does not exist a single weakest oracle, but a weakest family of oracles $$\zeta _n$$ : every two oracles in $$\zeta _n$$ are incomparable, and every oracle that allows for solving renaming provides at least as much information about failures as one of the oracles in $$\zeta _n$$ . As a by product, we obtain one more evidence that renaming is strictly easier to solve than set agreement.

The election problem in asynchronous distributed systems with bounded faulty processes

Determining the "weakest" failure detectors is a central topic in solving many agreement problems such as Consensus, Non-Blocking Atomic Commit and Election in asynchronous distributed systems. So far, this has been studied extensively for several such fundamental problems. It is stated that Perfect Failure Detector P is the weakest failure detector to solve the Election problem with any number of faulty processes. In this paper, we introduce Modal failure detector M and show that to solve Election, M is the weakest failure detector to solve election when the number of faulty processes is less than ?n/2?. We also show that it is strictly weaker than P.

The weakest failure detector to solve nonuniform consensus

We determine the weakest failure detector to solve nonuniform consensus in any environment, i.e., regardless of the number of faulty processes. Together with previous results, this closes all aspects of the following question: What is the weakest failure detector to solve (uniform or nonuniform) consensus in any environment?

On the weakest failure detector for hard agreement problems

Abstract Chandra and Toueg [J. ACM 43 (1996) 225] and Fromentin et al. [Proc. IEEE Internat. Conf. on Distrib. Comput., 1999, p. 470], respectively, stated that the weakest failure detector for any of non-blocking atomic commitment and terminating reliable broadcast is the perfect failure detector P . Recently, Guerraoui [IPL 79 (2001) 99] presented a counterexample of those results, exhibiting a failure detector called Marabout ( M ) that is incomparable to P and yet solves those problems. In this paper we present three new perfect failure detector classes as alternatives to P and M . All our classes are weaker than P . Furthermore, two of them are also weaker than M , and yet solve non-blocking atomic commitment and terminating reliable broadcast. Interestingly, our failure detector classes are implementable whenever P is implementable (e.g., in a synchronous system), which is not the case with M .

Reliability-based structural optimization under hazard loads

The present paper studies the reliability-based structural optimization of the civil engineering in the seismic zone. The objective is to minimize the sum of construction material cost and the expected failure loss under severe earthquake, which is obtained by the sum of the products of the failure probability and its failure losses for the important failure modes. The set of constraints includes the deterministic constraints, and the constraints based on structural reliability—the reliability index constraints of structural element failure for the serviceability state under minor earthquake and the failure probability of the structural system for the ultimate limit state under severe earthquake. By introducing the load roughness index, the structural system reliability computation under hazard load can be greatly simplified, which is approximately determined by its weakest failure mode. Finally, the numerical example of high rising shear RC frame is calculated.