4,763 research outputs found
Thermal-Aware Test Scheduling for Core-Based SoC in an Abort-on-First-Fail Test Environment
Long test application time and high temperature have become two major issues of system-on-chip (SoC) test. In order to minimize test application times and avoid overheating during tests, we propose a thermal-aware test scheduling technique for core-based SoC in an abort-on-first-fail (AOFF) test environment. The AOFF environment assumes that the test process is terminated as soon as the first fault is detected, which is usually deployed in volume production test. To avoid high temperature, test sets are partitioned into test sub-sequences which are separated by cooling periods. The proposed test scheduling technique utilizes instantaneous thermal simulation results to guide the partitioning of test sets and to determine the lengths of cooling periods. Experimental results have shown that the proposed technique is efficient to minimize the expected test application time while keeping the temperatures of cores under test below the imposed temperature limit
rDLB: A Novel Approach for Robust Dynamic Load Balancing of Scientific Applications with Parallel Independent Tasks
Scientific applications often contain large and computationally intensive
parallel loops. Dynamic loop self scheduling (DLS) is used to achieve a
balanced load execution of such applications on high performance computing
(HPC) systems. Large HPC systems are vulnerable to processors or node failures
and perturbations in the availability of resources. Most self-scheduling
approaches do not consider fault-tolerant scheduling or depend on failure or
perturbation detection and react by rescheduling failed tasks. In this work, a
robust dynamic load balancing (rDLB) approach is proposed for the robust self
scheduling of independent tasks. The proposed approach is proactive and does
not depend on failure or perturbation detection. The theoretical analysis of
the proposed approach shows that it is linearly scalable and its cost decrease
quadratically by increasing the system size. rDLB is integrated into an MPI DLS
library to evaluate its performance experimentally with two computationally
intensive scientific applications. Results show that rDLB enables the tolerance
of up to (P minus one) processor failures, where P is the number of processors
executing an application. In the presence of perturbations, rDLB boosted the
robustness of DLS techniques up to 30 times and decreased application execution
time up to 7 times compared to their counterparts without rDLB
F-8C adaptive flight control extensions
An adaptive concept which combines gain-scheduled control laws with explicit maximum likelihood estimation (MLE) identification to provide the scheduling values is described. The MLE algorithm was improved by incorporating attitude data, estimating gust statistics for setting filter gains, and improving parameter tracking during changing flight conditions. A lateral MLE algorithm was designed to improve true air speed and angle of attack estimates during lateral maneuvers. Relationships between the pitch axis sensors inherent in the MLE design were examined and used for sensor failure detection. Design details and simulation performance are presented for each of the three areas investigated
Reusable Centaur study. Volume 1: Executive summary
A study of the Reusable Centaur for use as an initial upper stage with the space shuttle was conducted. The currently operative Centaur stage, with modifications for space shuttle orbiter compatibility and for improved performance, represents a cost effective development solution. The performance needs and available development funds are discussed. The main features of three Reusable Centaur configurations with increasing capability at increasing development costs are summarized
Development of control systems for space shuttle vehicles, volume 1
Control of winged two-stage space shuttle vehicles was investigated. Control requirements were determined and systems capable of meeting these requirements were synthesized. Control requirements unique to shuttles were identified. It is shown that these requirements can be satisfied by conventional control logics. Linear gain schedule controllers predominate. Actuator saturations require nonlinear compensation in some of the control systems
Beam Loss Monitors at LHC
One of the main functions of the LHC beam loss measurement system is the
protection of equipment against damage caused by impacting particles creating
secondary showers and their energy dissipation in the matter. Reliability
requirements are scaled according to the acceptable consequences and the
frequency of particle impact events on equipment. Increasing reliability often
leads to more complex systems. The downside of complexity is a reduction of
availability; therefore, an optimum has to be found for these conflicting
requirements. A detailed review of selected concepts and solutions for the LHC
system will be given to show approaches used in various parts of the system
from the sensors, signal processing, and software implementations to the
requirements for operation and documentation.Comment: 16 pages, contribution to the 2014 Joint International Accelerator
School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14
Nov 201
Implementing atomic actions in Ada 95
Atomic actions are an important dynamic structuring technique that aid the construction of fault-tolerant concurrent systems. Although they were developed some years ago, none of the well-known commercially-available programming languages directly support their use. This paper summarizes software fault tolerance techniques for concurrent systems, evaluates the Ada 95 programming language from the perspective of its support for software fault tolerance, and shows how Ada 95 can be used to implement software fault tolerance techniques. In particular, it shows how packages, protected objects, requeue, exceptions, asynchronous transfer of control, tagged types, and controlled types can be used as building blocks from which to construct atomic actions with forward and backward error recovery, which are resilient to deserter tasks and task abortion
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