Ma Shilong

A Method of Analysis and Verification for Safety-Critical Software Based on Modelling and Testing

Currently how to ensure the reliability of safety-critical software is an urgent research. The center of our work is to study the analysis and verification method of spacecraft safety-critical software base on dynamical system to attain the objectives of result predication, status control and requirement verification, which can provide a theory and technical framework for safety-critical software.

Study on Wireless Sensor Networks

Constant advances in Micro Electro-Mechanical System (MEMS) technology promote miniaturization, low-cost and energy-efficiency of smart sensors. Meanwhile, Wireless Sensor Networks (WSNs) emerge as a collaborative network composed of such numerous sensors via wireless communication integrated. WSNs have a wide range of applications in the physical world, such as military surveillance, target tracking, healthcare etc. This paper illustrates a comprehensive study we contribute to in overviews, design ingredients, protocol architecture, the current research focus and the development status for WSNs with a contemporary view.

Centers, foci, and limit cycles for polynomial differential systems

Publisher Summary This chapter reviews some symbolic approaches based on characteristic sets, triangular systems, Grobner bases, resultants, and Sturm-like theorems, and summarizes a number of results achieved by using these approaches for cubic differential systems. Besides these general bounds for general systems, the existence of limit cycles and the related problem of centers and foci have also been studied for some specific systems such as cubic ones. Some problems and results for concrete (cubic) systems are reviewed, and symbolic computation and manipulation for polynomials arising from these problems are emphasized. For different classes of cubic systems, six, seven, and eight small-amplitude limit cycles may be constructed. The relationship among the independently obtained center conditions is explained, and necessary and sufficient conditions for the system to have two centers are also given. New conditions on the existence of eight limit cycles for a class of cubic differential systems were derived by solving a system of large polynomial equations and inequalities. The introduction of more variables may increase the computational complexity sharply, and thus make the method not work for large polynomial inequalities. A survey of the work for bifurcating small-amplitude limit cycles for cubic systems using symbolic computation and computer algebra systems is also elaborated in this chapter.

Researches on real-time satellite data flow processing based on file buffer

In the field of aerospace, all of real-time data sent by satellites and spaceships need to be stored into a relational database, and it is essential to develop real-time applications in order to implement the storing process automatically. Based on the implementation of a real-time satellite data flow storing application, this paper introduces features of real-time satellite data processing problem, and design architecture of pipeline-filter style as the framework of the application. As the indeterminacy of duration of insert operation in non-real-time database and the limited memory in the server, a method using the file to implement blocking queue for fault-tolerance is designed. With the pipeline/filter architecture design and the file blocking queue buffer method, a detail of implementation and an overall solution of application deployment are provided. In order to verify that the method of the file blocking queue has a better performance than that of the memory blocking queue, a comparative experiment simulating a real environment is designed. Our work proves that it is feasible and rational to use the file buffer in the specific application including non-real-time factors; in addition a non-real-time database can be used in the field of real-time with the proper mechanism of fault-tolerance.

Research on spacecraft automatic test system

In order to effectively solve the contradiction between the backward spacecraft technology and the booming demand of the current testing requirement, through analyzing the spacecraft automatic test principle, this paper puts forward a layered spacecraft automatic test system and its system architecture,which achieving the unified access to test-data and unified access to test-equipment with the implementation of the test-data management platform and test-resource management platform. This integrated access management further improves the universality of automatic test system.

An automatic testing framework applied on LIW and its implementation

Software is an important component of Large Information Weapon. We propose a data-driven distributed automatic testing framework, which is based on the analysis of LIW testing requirements, and it supports the whole process of testing. As an application of the framework, we develop an automatic testing system(DMATS). DMATS has been put into practices in XXX-business electronic system, and it is proved the feasibility of the framework.

Realization of UCON Model Based on Extended-XACML

Usage control model is presented and has been considered as the next generation control model which is used to access digital objects. in order to achieve full functionality of UCON, this paper puts forward a realization of UCON Model Based on extended-XACML ¨CeXUCON. First, We extended the policy decision point in XACML to support administrate conditions obligations and attributions of subject or object. Second, we established a eXUCON context model and find the differents between eXUCON context model and XACML context model. Finally, the potential of our realization for improving the convenience of enforcement mechanisms is illustrated using a small, but representative example.

A dynamic data document generating method in spacecraft test

Document resource always plays the key role in spacecraft testing. To make up for the deficiency of the current solutions in the domain of report automatic generation, this paper presents a generation model for dynamic data report, and introduces the data model and template model in this generation model. The design of the report automatic generation tool based on this model is expounded and compared with the existing report generation technology.

Well limit behaviors of term rewriting systems

The limit behaviors of computations have not been fully explored. It is necessary to consider such limit behaviors when we consider the properties of infinite objects in computer science, such as infinite logic programs, the symbolic solutions of infinite polynomial equations. Usually, we can use finite objects to approximate infinite objects, and we should know what kinds of infinite objects are approximable and how to approximate them effectively. A sequence {Rk: k ε ω} of term rewriting systems has the well limit behavior if under the condition that the sequence has the set-theoretic limit or the distance-based limit, the sequence {Th(Rk): k ε ω} of corresponding theoretic closures of Rk has the set-theoretic or distance-based limit, and limk→∞Th(Rk) is equal to the theoretic closure of the limit of {Rk: k ε ω}. Two kinds of limits of term rewriting systems are considered: one is based on the set-theoretic limit, the other is on the distance-based limit. It is proved that given a sequence {Rk: κ ε ω} of term rewriting systems Rk, if there is a well-founded ordering ≺ on terms such that every Rk is ≺-well-founded, and the set-theoretic limit of {Rk: κ ε ω} exists, then {Rk: κ ε ω} has the well limit behavior; and if (1) there is a well-founded ordering ≺ on terms such that every Rk is ≺-well-founded, (2) there is a distance d on terms which is closed under substitutions and contexts and (3) {Rk: k ε ω} is Cauchy under d then {Rκ: κ ε ω} has the well limit behavior. The results are used to approximate the least Herbrand models of infinite Horn logic programs and real Horn logic programs, and the solutions and Gröbner bases of (infinite) sets of real polynomials by sequences of (finite) sets of rational polynomials.