Android malware has been in an increasing trend in recent years due to the pervasiveness of Android operating system. Android malware is installed and run on the smartphones without explicitly prompting the users or without the user's permission, and it poses great threats to users such as the leakage of personal information and advanced fraud. To address these threats, various techniques are proposed by researchers and practitioners. Static analysis is one of these techniques, which is widely applied to Android malware detection and can detect malware quickly and prohibit malware before installation. To provide a clarified overview of the latest work in Android malware detection using static analysis, we perform a systematic literature review by identifying 98 studies from January 2014 to March 2020. Based on the features of applications, we first divide static analysis in Android malware detection into four categories, which include Android characteristic-based method, opcode-based method, program graph-based method, and symbolic execution-based method. Then we assess the malware detection capability of static analysis, and we compare the performance of different models in Android malware detection by analyzing the results of empirical evidence. Finally, it is concluded that static analysis is effective to detect Android malware. Moreover, there is a preliminary result that neural network model outperforms the non-neural network model in Android malware detection. However, static analysis still faces many challenges. Thus, it is necessary to derive some novel techniques for improving Android malware detection based on the current research community. Moreover, it is essential to establish a unified platform that is used to evaluate the performance of a series of techniques in Android malware detection fairly. INDEX TERMS Android malware detection, static analysis, systematic literature review.

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Under the software quality management mechanism, developers are generally required to review and test their own code firstly to ensure that the submitted code meets specific quality standards. At the same time, with the popularity of test-driven development (TDD) and extreme programming (XP), programming and testing are complementary in the process of software development, i.e., software testing has become as important as programming. Despite its importance, there is no empirical study that investigates the ability relationships between programming and testing. This paper presents such a study, where we designed software tasks to investigate the ability of programming and testing. We distributed the program tasks to software vocational students and analyzed the results from multiple dimensions. Our main findings show that (i) almost half of the developers with strong programming ability do not have a good testing ability; (ii) some developers with weak programming ability can do well in testing; (iii) compared with programming ability, testing fundamentals have a greater impact on the testing ability; and (iv) most developers can do well at finding bugs but lack experience in writing test scripts. INDEX TERMS software testing, programming ability, testing ability

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Based on reduced model of Double-Fed Direct Current Motor System (DFDCMS), the state space description and its key states of DFDCMS are advanced. The two wheeled robot's kinematics model and Motion-Actuator model are analyzed, the state observer based on Extended Kalman Filter(EKF) of the Two Wheels Mobile Robot(TWMR) is used to filter the signal with interference and get the key states. There are tree kinds of state observers, including the direct state observer with nothing filter(NF) ,the state observer with Butterworth Filter(BF) and the state observer with EKF, are used to compare on two kinds of experiment platform, including the simulation system and the fact system of RoboCup soccer robot. As an application example, the motion states of TWMR have been analyzed base on EKF state observer during the course of TWMR going to one goal. The experimentation indicates that the state observer based on EKF can reflect the running states of test system more availably. Index Terms -Two wheeled robot, DC motor system model, Kalman filter, State observe