1,720,998 research outputs found
Zero-laxity based real-time multiprocessor scheduling
No full textIt has been widely studied how to schedule real-time tasks on multiprocessor platforms. Several studies have developed optimal scheduling policies for implicit deadline task systems. So far however, studies have failed to develop effective scheduling strategies for more general task systems such as constrained deadline tasks. We argue that a narrow focus on deadline satisfaction (urgency) is the primary reason for this lack of success. In particular, few studies have considered the impact on scheduling of the restriction that a job cannot simultaneously execute on more than one core (parallelism). In this paper we look at one such simple, but effective, characterization of urgency and parallelism - the zero laxity first policy (ZL policy). We study in detail how beneficial the ZL policy is to schedulability. We then develop an improved schedulability test for any algorithm that employs the ZL policy, and prove that the test dominates previously known tests. Our simulation results show that the improved ZL schedulability test outperforms the existing ones. (C) 2011 Elsevier Inc. All rights reserved.
Mobile Maestro: Enabling Immersive Multi-Speaker Audio Applications on Commodity Mobile Devices
No full text
A Coordinated Sensing Flow Execution Engine for Concurrent Mobile Sensing Applications
No full textA mobile apparatus includes a sensing handler and a processing handler. The sensing handler includes a plurality of sensing operators. The sensing operator senses data during a sensing time corresponding to a size of C-FRAME and stops sensing during a skip time. The C-FRAME is a sequence of the sensed data to produce a context monitoring result. The processing handler includes a plurality of processing operators. The processing operator executes the sensed data of the sensing operator in a unit of F-FRAME. The F-FRAME is a sequence of the sensed data to execute a feature extraction operation
Composition of Schedulability Analyses for Real-Time Multiprocessor Systems
No full textWith increasing popularity and deployment of multi-core chips in embedded systems, a number of real-time multiprocessor scheduling algorithms have been proposed along with their schedulability analyses (or tests), which verify temporal correctness under a specific algorithm. Each of these algorithms often comes with several different schedulability tests, especially when it is difficult to find exact schedulability tests for the algorithm. Such tests usually find different task sets deemed schedulable even under the same scheduling algorithm. While these different tests have been compared with each other in terms of schedulability performance, little has been done on how to combine such different tests to improve the overall schedulability of a given scheduling algorithm beyond a simple union of their individual schedulability. Motivated by this, we propose a composition theory for schedulability tests with two new methods. The first method composes task-level timing guarantees derived from different schedulability tests, and the second one derives system-level schedulability results from a single schedulability test. The unified composition theory with these two methods then utilizes existing schedulability tests effectively so as to cover additional schedulable task sets. The proposed composition theory is shown to be applicable to most existing preemptive/non-preemptive scheduling algorithms. We also present three case-studies, demonstrating how and by how much the theory can improve schedulability by composing existing schedulability tests. Our evaluation results also show that the composition theory makes it possible to cover up to 181.7 percent additional schedulable task sets for preemptive fpEDF, preemptive EDF and non-preemptive EDF scheduling algorithms beyond their existing tests.MOE (Min. of Education, S’pore)Accepted versio
The influences of string tension and frame stiffness on racquet and ball motions, and on impact loads at the elbow joint during the tennis backhand drive
No full textThe motion of the ball and frame during and just after impact was inferred from the acceleration-time change of an accelerometer instrumented impactor pendulum, and the strain-time change of the frame during the clamped racket impact. The impulsive loads acting on the elbow joint were estimated by adopting an inverse dynamic analysis (impulse-momentum equation) for the racket and forearm during the backhand drive.The stiffness and string tension conditions tested in the experiment were 5450 and 7540 N/m crossed with 178,245, and 311 N, respectively for the two phases of tests. Generally, the impulse of the first acceleration spike was not consistently affected by the string tension and frame stiffness. However, at the slowest impact speed, high string tension and flexible frame significantly reduced the impulse on the ball. This specific result was partly consistent with the impulse measured in actual backhand drive impact where only the tighter string reduced the impulse applied to the ball. Although the mean impulses produced by the stiff frame were larger than those by flexible frame at the tested string tensions, the difference was not significant.The mean linear and angular impulses acting on the elbow joint during backhand drive were 0.804 N sec and 0.416 N sec, respectively, with large variability in the measures. The approximated peak impulsive force and moment was 144 N and 78 Nm respectively. The effect of different string tension and frame stiffness on the impulsive loads at the elbow joint during backhand drive was not significant.Recommendations. A lighter impactor would improve the applicability of the impactor pendulum results to actual racket and ball interaction. A set of 3-D impulse-momentum equations need to be developed for incorporation into 3-D motion analysis.Made available in DSpace on 2011-05-07T11:56:32Z (GMT). No. of bitstreams: 2
license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5)
9011021.pdf: 4615865 bytes, checksum: e08a2bbc90af1cdbe79144fcf055dbaf (MD5)
Previous issue date: 1989Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:34:34Z
Item is restricted indefinitely.Restriction data tranferred 2014-07-01T11:13:16-05:00
Original Data
Group with Access UIUC Users [automated]
Release Date: none
Reason: ETDs are only available to UIUC Users without author permissionETDs are only available to UIUC Users without author permissionU of I Onl
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
GreenBag : 이기종 모바일 무선 네트워크에서 실시간 스트리밍을 위한 전력 효율 대역폭 병합기술
No full text학위논문(석사) - 한국과학기술원 : 전산학과, 2013.8, [ v, 28 p. ]Modern mobile devices are equipped with multiple network interfaces, including 3G/LTE and WiFi. Bandwidth aggregation over LTE and WiFi links offers an attractive opportunity of supporting bandwidth-intensive services, such as high-quality video streaming, on mobile devices. However, achieving effective bandwidth aggregation in mobile environments raises several challenges related to deployment, link heterogeneity, network fluctuation, and energy consumption. We present GreenBag, an energy-efficient bandwidth aggregation middleware that supports real-time data-streaming services over asymmetric wireless links, requiring no modifications to the existing Internet infrastructure. GreenBag employs several techniques, including medium load balancing, efficient segment management, and energy-aware mode control, to resolve such challenges. We implement a prototype of GreenBag on Android-based mobile devices which hosts, to the best knowledge of the authors, the first LTE-enabled bandwidth aggregation prototype for energy-efficient real-time video streaming. Our experiment results in both emulated and real-world environments show that GreenBag not only achieves good bandwidth aggregation to provide QoS in bandwidth-scarce environments but also efficiently saves energy on mobile devices. Moreover, energy-aware GreenBag can minimize video interruption while consuming 14-25% less energy than the non-energy-aware counterpart in real-world experiments.한국과학기술원 : 전산학과
- …
