53 research outputs found
Scheduling and Allocation in Multiprocessor Systems
The problem of allocation has always been one of the fundamental issues of
building applications in multiprocessor systems. For real-time applications,
the allocation problem should directly address the issues of task and
communication scheduling. In this context, the allocation of
tasks has to fully utilize the available processors and the scheduling
of tasks has to meet the specified timing constraints. Clearly,
the execution of tasks under the allocation and schedule has to satisfy
the precedence, resources, and synchronization constraints.
Traditionally time constraints for real-time tasks have been specified
in terms of ready time and deadlines. Many application tasks have relative
timing constraints in which the constraints for the execution of a task
are defined in terms of the actual execution instances of prior tasks.
In this dissertation we consider the allocation and scheduling problem of
the periodic tasks with relative timing requirements. We take a time-based
scheduling approach to generate a multiprocessor schedule for a set of
periodic tasks. A simulated annealing algorithm is developed as the
overall search algorithm for a feasible solution. Our results show that
the algorithm performs well and finds feasible allocation and scheduling.
We also investigate how to exploit the replication technique to increase
the schedulability and performance of the systems. In this dissertation,
we adopt the computation model in which each task may have more than one
copy and a task may start its execution after receiving necessary data
from a copy of each of its predecessors. Based on this model,
replication techniques are developed to increase the schedulability of the
applications in real-time systems and to reduce the execution cost of
the applications in non-real-time systems
Comment on "A special attack on the multiparty quantum secret sharing of secure direct communication using single photons"
In this comment, we show that the special attack [S.-J. Qin, F. Gao, Q.-Y.
Wen, F.-C. Zhu, Opt. Commun. 281 (2008) 5472.], which claims to be able to
obtain all the transmitted secret message bit values of the protocol of the
multiparty quantum secret sharing of secure direct communication using single
photons with random phase shift operations, fails. Furthermore, a class of
similar attacks are also shown to fail to extract the secrete message.Comment: 2 pages (two-column
Recent work on sprite spectrum in Taiwan
campaigns in Taiwan. We first introduce two types of spectroimagers, the slit and slitless types, and discuss their advantages and shortcomings. Next we explore the instrument development and procedures undertaken for this study. In 2006, a slit spectroimager was installed for a sprite campaign and on 15 August of that year, two sprite spectra were recorded using the slit spectroimager along with seven sprites, one halo, one ELVES emission and two jets. By the end of 2015, a slitless spectroimager had been successfully constructed and was ready to conduct additional investigations. On 7 May 2016, a sprite spectrum was recorded using the slitless spectroimager. Following an examination of the calibrations (comprising detection region field of view, wavelength calibration, and response curve), data analysis, and additional calibrations (comprising elevation and azimuthal angles, atmospheric transmittance, and theoretical wavelength calculations) performed in this study, we present the results from our observed sprite spectra using the slit and slitless spectroimagers
The gene normalization task in BioCreative III
BACKGROUND: We report the Gene Normalization (GN) challenge in BioCreative III where participating teams were asked to return a ranked list of identifiers of the genes detected in full-text articles. For training, 32 fully and 500 partially annotated articles were prepared. A total of 507 articles were selected as the test set. Due to the high annotation cost, it was not feasible to obtain gold-standard human annotations for all test articles. Instead, we developed an Expectation Maximization (EM) algorithm approach for choosing a small number of test articles for manual annotation that were most capable of differentiating team performance. Moreover, the same algorithm was subsequently used for inferring ground truth based solely on team submissions. We report team performance on both gold standard and inferred ground truth using a newly proposed metric called Threshold Average Precision (TAP-k).
RESULTS: We received a total of 37 runs from 14 different teams for the task. When evaluated using the gold-standard annotations of the 50 articles, the highest TAP-k scores were 0.3297 (k=5), 0.3538 (k=10), and 0.3535 (k=20), respectively. Higher TAP-k scores of 0.4916 (k=5, 10, 20) were observed when evaluated using the inferred ground truth over the full test set. When combining team results using machine learning, the best composite system achieved TAP-k scores of 0.3707 (k=5), 0.4311 (k=10), and 0.4477 (k=20) on the gold standard, representing improvements of 12.4%, 21.8%, and 26.6% over the best team results, respectively.
CONCLUSIONS: By using full text and being species non-specific, the GN task in BioCreative III has moved closer to a real literature curation task than similar tasks in the past and presents additional challenges for the text mining community, as revealed in the overall team results. By evaluating teams using the gold standard, we show that the EM algorithm allows team submissions to be differentiated while keeping the manual annotation effort feasible. Using the inferred ground truth we show measures of comparative performance between teams. Finally, by comparing team rankings on gold standard vs. inferred ground truth, we further demonstrate that the inferred ground truth is as effective as the gold standard for detecting good team performance
Optimal Replication of Series-Parallel Graphs for Computation-Intensive Applications
We consider the replication problem of series-parallel (SP) task
graphs where each task may run on more than one processor. The objective
of the problem is to minimize the total cost of task execution and
interprocessor communication. We call it, the minimum cost replication
problem for SP graphs (MCRP-SP). In this paper, we adopt a new
communication model where the purpose of replication is to reduce the
total cost. The class of applications we consider is
computation-intensive applications in which the execution cost of a task
is greater than its communication cost. The complexity of MCRP-SP for
such applications is proved to be NP-complete. We present a
branch-and-bound method to find an optimal solution as well as an
approximation approach for suboptimal solution. The numerical results
show that such replication may lead to a lower cost than the optimal
assignment problem (in which each task is assigned to only one processor)
does. The proposed optimal solution has the complexity of O(n22nM), while
the approximation solution has O(n4M2), where n is the number of
processors in the system and M is the number of tasks in the graph.
(Also cross-referenced as UMIACS-TR-93-4.1
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