Comparative Analysis of Limit Bearing Capacity of a Continuous Beam Depending on the Character of the Load

Determination of the bearing capacity of a structure, as well as the assessment related tothe structure failure is very valuable, not only as a simple control of beam bearing capacity,but also as a significant basis and factor in designing of structures. When the structure isexposed to the action of a proportionally increasing load, by applying the limit analysis it ispossible to determine the limit failure load which is one of the bearing capacity indicators. Inthe case when beam systems are exposed to repeated load, the limit theorems do not yield the adequate solutions, thus the adaptation theorems which made safe limit load determination possible were developed simultaneously. Applying the limit and shakedown analysis, the analysis of bearing capacity of a continuous beam with two spans was conducted in the paper.Also displayed is the difference between the values of failure forces depending on the character of load and the beam span value in order to assess justification for application of the shakedown method in the analysis of the limit bearing capacity of the beams

Robust and Fast Blockchain State Synchronization

State synchronization, the process by which a new or recovering peer catches up with the state of other operational peers, is critical to the operation of blockchain-based systems. Existing approaches to state synchronization typically involve downloading snapshots of system state. Such approaches introduce an attack vector from malicious peers that can significantly degrade performance. Moreover, the process of creating snapshots leads to performance hiccups. This paper presents a technique for peers to catch up with operational peers without trusting any particular peer and gracefully recover from misbehavior during the process. We have integrated our design into a production blockchain middleware. Our evaluation shows that during operation, the transaction throughput is consistently higher without pauses for snapshot construction. Moreover, the time it takes for a new peer to join the blockchain is halved, while at the same time tolerating Byzantine peers

Computational modeling of shear forces and experimental validation of endothelial cell responses in an orbital well shaker system

Vascular endothelial cells are continuously exposed to hemodynamic shear stress. Intensity and type of shear stress are highly relevant to vascular physiology and pathology. Here, we modeled shear stress distribution in a tissue culture well (R = 17.5 mm, fill volume 2 ml) under orbital translation using computational fluid dynamics with the finite element method. Free surface distribution, wall shear stress, inclination angle, drag force, and oscillatory index on the bottom surface were modeled. Obtained results predict nonuniform shear stress distribution during cycle, with higher oscillatory shear index, higher drag force values, higher circular component, and larger inclination angle of the shear stress at the periphery of the well compared with the center of the well. The oscillatory index, inclination angle, and drag force are new quantitative parameters modeled in this system, which provide a better understanding of the hydrodynamic conditions experienced and reflect the pulsatile character of blood flow in vivo. Validation experiments revealed that endothelial cells at the well periphery aligned under flow and increased Kruppel-like Factor 4 (KLF-4), cyclooxygenase-2 (COX-2) expression and endothelial nitric oxide synthase (eNOS) phosphorylation. In contrast, endothelial cells at the center of the well did not show clear directional alignment, did not induce the expression of KLF-4 and COX-2 nor increased eNOS phosphorylation. In conclusion, this improved computational modeling predicts that the orbital shaker model generates different hydrodynamic conditions at the periphery versus the center of the well eliciting divergent endothelial cell responses. The possibility of generating different hydrodynamic conditions in the same well makes this model highly attractive to study responses of distinct regions of the same endothelial monolayer to different types of shear stresses thereby better reflecting in vivo conditions

Tolerating permanent and transient value faults

Transmission faults allow us to reason about permanent and transient value faults in a uniform way. However, all existing solutions to consensus in this model are either in the synchronous system, or require strong conditions for termination, that exclude the case where all messages of a process can be corrupted. In this paper we introduce eventual consistency in order to overcome this limitation. Eventual consistency denotes the existence of rounds in which processes receive the same set of messages. We show how eventually consistent rounds can be simulated from eventually synchronous rounds, and how eventually consistent rounds can be used to solve consensus. Depending on the nature and number of permanent and transient transmission faults, we obtain different conditions on $$n$$ n , the number of processes, in order to solve consensus in our weak model

Generic construction of consensus algorithms for benign and Byzantine faults

The paper proposes a generic consensus algorithm that highlights the basic and common features of known consensus algorithms. The parameters of the generic algorithm encapsulate the core differences between various consensus algorithms, including leader-based and leader-free algorithms, addressing benign faults, authenticated Byzantine faults and Byzantine faults. This leads to the identification of three classes of consensus algorithms. With the proposed classification, Paxos and PBFT indeed belong to the same class, while FaB Paxos belongs to a different class. Interestingly, the classification allowed us to identify a new Byzantine consensus algorithm that requires n>4b, where b is the maximum number of Byzantine processes

Tolerating permanent and transient value faults

Transmission faults allow us to reason about permanent and transient value faults in a uniform way. However, all existing solutions to consensus in this model are either in the synchronous system, or require strong conditions for termination, that exclude the case where all messages of a process can be corrupted. In this paper we introduce eventual consistency in order to overcome this limitation. Eventual consistency denotes the existence of rounds in which processes receive the same set of messages. We show how eventually consistent rounds can be simulated from eventually synchronous rounds, and how eventually consistent rounds can be used to solve consensus. Depending on the nature and number of permanent and transient transmission faults, we obtain different conditions on , the number of processes, in order to solve consensus in our weak model