The need for safety critical systems (SCS) is both important and urgent, and their evaluation and verification are test-dependent. SCS are usually complex and very large, so manual testing of SCS are infeasible in practice, and developing automatic test approaches for SCS has become an important trend. This paper defines a formal semantics model for automatic test of SCS, called AutTMSCS, which describes behaviors in SCS testing. The model accommodates the high order collaboration in real time and temporariness of SCS testing. Testing tasks, test equipment and products under test are abstracted and architected in three layers, and a method for automatic testing is given. Based on extended label transition system (LTS), the convergency and correctness of the model are proved to demonstrate the computability of the model, indicating that the testing process of SCS can be automatic.
In this paper, a Database Experiment System (DES) based web was introduced to provide the students an easy and convenient learning environment. The aim of the DES will easily make the students to experiment database by a browser on a computer terminal linked to Internet anywhere rather than in a special laboratory. There are a rich test questions in the system and every questions will be based a special project.The online experiment function lets the students run SQL scripts repeatedly until satisfy their requirements. Another more important advantage is that the experiment data can be assessed by the system automatically. The DES adopted the method of Object-Oriented modeling with UML and is composed of a 3-tier architecture based on B/S. All the applications' design and coding are based on the architecture of Microsoft .Net in the system. The Fa�ade pattern is introduced to achieve security of the system. The DES consists of five functions and they are Manage Users, Manage Test Questions, Manage Experiment, Value Experiment and Experimentalize. The design of the Machine of Assessment as the most important function of DES was particularly discussed in the paper. It fulfilled valuing the students experiment data automatically by the computer and mark the experiment. The DES has applied for two academic years and achieved a satisfied result.
As more and more parallel programs are migrating to shared computing platforms, bounding their parallel execution times under resource constraints is particularly important for their efficient executions. The parallel program is often modeled as a task graph, which is composed of a collection of control or data-dependent sub-tasks organized as a directed acyclic graph (DAG) for scheduling. In this paper, we propose a simple yet effective method to bound the parallel execution time of a task graph when the memory resources are constrained. The essence of this method is to extend Brent's theorem by incorporating the memory factor. To this end, we introduce a concept of range of concurrent tasks (RCT) and leverage it to estimate an upper bound on the parallel execution time of task graph with respect to work-conserving scheduling algorithm. And also we exploit the estimated bound to develop a metric to help determine optimal memory capacity for a given task graph. Through an empirical study, we evaluate how good the estimated bound is via a designed scheduling algorithm and demonstrate the effectiveness of the metric in the selection of optimal memory capacity for a task graph. INDEX TERMS Task graph scheduling, time bounds, parallel execution, multicores, shared memory, memory constraints.
In this paper, a new concept that is Circulation Course Resources (CCR) is introduced, which means the course resources circulating from the students listening in classroom lecture, camera shooting, video coding, video storage, video server to the students learning from VOD. The creating course video system and network-teaching system as parts of CCR architecture are presented separately. To connect the two systems, a middle system defined as Bridge System is designed and modeled with UML. The core application design of the Bridge System is expressed by the classes design and main database design. The functions of Bridge System include making the course videos flowing from one system to another automatically and converting the important data of the two systems into uniform format. The CCR architecture has been put into action and achieved satisfied results.
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