The effect of possible accidental beam loss in the LHC on the IP5 and IP6 insertion elements is studied via realistic Monte Carlo simulations. The scenario studied is beam loss due to unsynchronized abort at an accidental prefire of one of the abort kicker modules. Simulations show that this beam loss would result in severe heating of the IP5 and IP6 superconducting (SC) quadrupoles. Contrary t...

This paper briefly summarizes some recent IBM work in the areas of distributed commit protocols, and recoverable messaging and queuing. We discuss the original presumed nothing commit protocol of SNA LU 6.2 and the current industry standard presumed abort (PA) protocol which we originally developed in IBM’s R* project. We also discuss generalized presumed abort (GPA) which resulted from the int...

Transaction States In our model of transactions, an update transaction, once started, updates the abstract database atomically when the transaction commits, or makes no changes in the database, when it aborts. We have represented the global state of update transactions by a variable transstatus in the abstract model of the transactions. The variable transtatus is defined as transtatus ∈ trans →...

This paper briefly summarizes some recent IBM work in the areas of distributed commit protocols, andrecoverable messaging and queuing. We discuss the original presumed nothing commit protocol of SNALU 6.2 and the current industry standard presumed abort (PA) protocol which we originally developedin IBM’s R* project. We also discuss generalized presumed abort (GPA) which resulted fro...

In mobile database environments, multiple users may access similar data items irrespective of their physical location leading to concurrent access anomalies. As disconnections and mobility are the common characteristics in mobile environment, performing concurrent access to a particular data item leads to inconsistency. Most of the approaches use locking mechanisms to achieve concurrency contro...

Camellia is one of the most worldwide used block ciphers, which has been selected as a standard by ISO/IEC. In this paper, we propose several new 7-round impossible differentials of Camellia with 2 FL/FL−1 layers, which turn out to be the first 7-round impossible differentials with 2 FL/FL−1 layers. Combined with some basic techniques including the early abort approach and the key schedule cons...

In order to examine whether stereoscopic depth information could drive fast automatic correction of hand pointing, an experiment was designed in a 3D visual environment in which participants were asked to point to a target at different stereoscopic depths as quickly and accurately as possible within a limited time window (≤300 ms). The experiment consisted of two tasks: "depthGO" in which parti...

Due to resource sharing among tasks, priority inversion can occur during prioritydriven preemptive scheduling. In this work, we investigate solutions to the priority inversion problem in a real-time database environment where two-phase locking is employed for concurrency control. We examine two basic schemes for addressing the priority inversion problem, one based on priority inheritance and th...

Checkpointing and closed nesting are mechanisms typically used for implementing partial roll-back in transactional systems. Closed nesting limits the amount of work to redo on an abort by allowing sub-transactions to abort and retry independently from their parents. Checkpointing goes further and allows a transaction to be rolled back to any previous point where a checkpoint was saved. Checkpoi...

Web servers become overloaded when one or several server resources are overutilized. In this paper we present an adaptive architecture that prevents resource overutilization in web servers by performing admission control based on application-level information found in HTTP headers and knowledge about resource consumption of requests. In addition, we use an efficient early discard mechanism that...