Vehicular communication systems are expected to be a key enabling technology for many benefits of Cooperative, Connected and Automated Mobility (CCAM) in terms of increased road safety, efficiency and decreased enviro...
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ISBN:
(纸本)9781665421034
Vehicular communication systems are expected to be a key enabling technology for many benefits of Cooperative, Connected and Automated Mobility (CCAM) in terms of increased road safety, efficiency and decreased environmental impact of road transport. For reliable and safe operation of these systems, a thorough performance evaluation under all possible deployment scenarios and varying traffic conditions must be performed. Computer simulation can help to considerably speed the performance evaluation and prototyping of novel CCAM services. However, to be realistic, development of CCAM simulation models requires an engagement of multidisciplinary knowledge. Moreover, since the commonly used simulation tools are rather complex, a specialized training for future CCAM experts on simulation of vehicular communication systems might be necessary. this paper provides an overview of existing simulation tools applicable for development and evaluation of vehicular communication systems and services, presents a simulation stack for realistic simulations based on key vehicular communication technologies (DSRC, LTE- and 5G-based C-V2X) and outlines the possibilities of its application in the educational process by analyzing the underlying technical skills necessary for appropriate placement of related course in existing curricula.
this paper proposes and implements a rigorous method for studying the dynamic behaviour of AspectJ programs. As part of this methodology several new metrics specific to AspectJ programs are proposed and tools for coll...
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ISBN:
(纸本)9781581138313
this paper proposes and implements a rigorous method for studying the dynamic behaviour of AspectJ programs. As part of this methodology several new metrics specific to AspectJ programs are proposed and tools for collecting the relevant metrics are presented. the major tools consist of: (1) a modified version of the AspectJ compiler that tags bytecode instructions with an indication of the cause of their generation, such as a particular feature of AspectJ; and (2) a modified version of the *J dynamic metrics collection tool which is composed of a JVMPI-based trace generator and an analyzer which propagates tags and computes the proposed metrics. this dynamic propagation is essential, and thus this paper contributes not only new metrics, but also non-trivial ways of computing *** furthermore present a set of benchmarks that exercise a wide range of AspectJ's features, and the metrics that we measured on these benchmarks. the results provide guidance to AspectJ users on how to avoid efficiency pitfalls, to AspectJ implementors on promising areas for future optimization, and to tool builders on ways to understand the runtime behaviour of AspectJ.
this paper introduces dynamic object colocation, an optimization to reduce copying costs in generational and other incremental garbage collectors by allocating connected objects together in the same space. Previous wo...
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ISBN:
(纸本)9781581138313
this paper introduces dynamicobject colocation, an optimization to reduce copying costs in generational and other incremental garbage collectors by allocating connected objects together in the same space. Previous work indicates that connected objects belong together because they often have similar lifetimes. Generational collectors, however, allocate all new objects in a nursery space. If these objects are connected to data structures residing in the mature space, the collector must copy them. Our solution is a cooperative optimization that exploits compiler analysis to make runtime allocation decisions. the compiler analysis discovers potential object connectivity for newly allocated objects. It then replaces these allocations with calls to coalloc, which takes an extra parameter called the colocatorobject. At runtime, coalloc determines the location of the colocator and allocates the new object together with it in either the nursery or mature space. Unlike pretenuring, colocation makes precise per-object allocation decisions and does not require lifetime analysis or allocation site homogeneity. Experimental results for SPEC Java benchmarks using Jikes RVM show colocation can reduce garbage collection time by 50% to 75%, and total performance by up to 1%.
this paper reports on the design and implementation of Chianti, a change impact analysis tool for Java that is implemented in the context of the Eclipse environment. Chianti analyzes two versions of an application and...
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ISBN:
(纸本)9781581138313
this paper reports on the design and implementation of Chianti, a change impact analysis tool for Java that is implemented in the context of the Eclipse environment. Chianti analyzes two versions of an application and decomposes their difference into a set of atomic changes. Change impact is then reported in terms of affected (regression or unit) tests whose execution behavior may have been modified by the applied changes. For each affected test, Chianti also determines a set of affecting changes that were responsible for the test's modified behavior. this latter step of isolating the changes that induce the failure of one specific test from those changes that only affect other tests can be used as a debugging technique in situations where a test fails unexpectedly after a long editing session. We evaluated Chianti on a year (2002) of CVS data from M. Ernst's Daikon system, and found that, on average, 52% of Daikon's unit tests are affected. Furthermore, each affected unit test, on average, is affected by only 3.95% of the atomic changes. these findings suggest that our change impact analysis is a promising technique for assisting developers with program understanding and debugging.
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