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Weak signal acquisition attracts global attention in GNSS research. Coherent losses caused by bit flipping lead to acquisition difficulty for traditional methods. An optimized semi-bit frequency compensated differential post-correlation processing is proposed through analyzing problems of the conventional differential post-correlation processing in this paper. The impact of data flipping is eliminated by the semi-bit time control logic, and the processing loss of carrier estimation error is improved by the carrier frequency compensation circuit. Theoretical analysis and simulation results show that the improved differential coherent accumulation technology can significantly improve the environment of weak signal detection probability of GNSS signals.

A new method of constructing optimal Gold-like binary sequence set is proposed. The sequence constructed is identical to the well known family of Gold sequences in terms of maximum nontrivial correlation magnitude and family size, while having fewer limitations such as few constraints, sharp auto correlation peak, and good global cross-correlation performance. With the concept of cyclical coset, the sequences are easily expanded with preferred pairs. Theoretical analysis and simulation results show that this method can significantly extend the sampling range of sequence structure and broaden the application of sequences compared with the construction method of traditional Gold binary sequence.

In order to detect the security of Android software which isn't installed efficiently and accurately, this paper proposes a new malware detection method based on system calls frequency. Software samples are pretreated by Classification to refine and distinguish characteristics of various types of Android software; Restrictions and normalization are applied to process system call frequency information to improve the detection accuracy. Combined with the characteristics of random forest algorithms and data obtained, optimal training model is set up, and ultimately Android software security is detected effectively. Through experiments, the detection accuracy rate of Android tool software and financial software more than 93 percent, with higher accuracy.

A remote manufacturing monitoring system based on sensors, RFID (Radio Frequency Identification) and network is designed for keeping track of information which industrial machines are evaluated with. Different sensors, such as, temperature transducer, pressure transducer, noise transducer, current sensor, revolution speed transducer, vibration frequency transducer and RFID tags, are employed in the system to collect information from the industrial machines. The lower-layer field data collection system is linked with the upper-layer monitoring and diagnosis application system via Zigbee, industry Ethernet and WiFi (Wireless Fidelity). The monitoring system is implemented on machine tools with a user friendly interface. The tests show that the system could check machine tool status efficiently. Both software and hardware implementation are demonstrated in this work.

The communication tasks of fieldbus system often include the information transfer among the field devices. However, fieldbus is not an absolute system, which is a component of entire system. Therefore, as to fieldbus scheduling, not only the communication tasks of fieldbus but also the restrains from the other tasks in the system should be considered. In this paper, a dynamic fieldbus scheduling algorithm is used to cope with the dynamic scheduling of the task system including cyclic real-time tasks, acyclic real-time tasks, non-real-time tasks and time slot tasks under distributed multi-processor system. The model of the task system is presented and the algorithm is designed. At last, a real-time communication scheduling of computer numerical control (CNC) fieldbus system is illustrated to apply the algorithm, and the time and space cost of this algorithm is analyzed.

To enhance real-time performance of the motion control level communication, the real-time performance and feasibility of Ethernet application in the motion control level is analyzed. Then, this paper proposes an optimization method for Ethernet-based real-time communication of Computer Numerical Control (CNC) system. By this method, the transmission delay in Ethernet is obtained in the time synchronization process, and it is used for efficiency modeling according to the time slot contention theory. Through analyzing the model on transmission delay, it can provide adaptive parameters to shape the traffic of sender nodes by themselves, to ensure the real-time performance and the determinability of the motion control level communication.