Applied Mechanics and Materials Vols. 40-41

Abstract: Requirements modeling is a critical stage in the development of ECUs (Electronic Control Unit) of automotive systems. A typical automotive system usually involves large amount of requirement items, and possesses restricted timing constraints and complicated interactions, therefore a single modeling language only does not cover the whole characteristics of a system. In this paper, we extend SaveCCM, a component model for automotive software development, with timed automata to form a modeling framework for automotive requirements. The integrated model can be used to analyze the architecture and timed behavior of an automotive system. The proposed approach takes the following advantages that: (1) It can effectively and completely express the architecture and behavior requirements of automotive systems; (2) It can describe the interactions between an ECU and its environment in terms of synchronization channels.

Abstract: Correctly modeling software requirements is one of the grand challenges of current ECU (Electronic control Unit) development. To ensure the correctness of the requirements, formal modeling techniques are usually used because they allow analyzers to simulate, verify and even conduct performance analysis in the requirement level. In this paper, we propose a requirements modeling framework, based on the philosophy of separation of concerns and the formal modeling techniques. The main contributions of this paper are two-fold: (1) We divide a complicated automotive software as several concerns, each of which is modeled by different formal techniques, thus the descriptive complexity of the requirements is decreased, and accordingly the models’ understandability is enhanced; (2) The adoption of formal techniques allows us to simulate the execution of the software and calculate the performance in the early stage of development, therefore the correctness of requirements can be improved.

Abstract: This paper analyzes the sources of high-tech spin-offs’ operational risks, establishes a multifactor hierarchical index system and applies Analytical Hierarchy Process and fuzzy mathematical methods to build a fuzzy overall evaluation model. This research can provide a useful tool to help high-tech spin-offs scientifically assess their operational risk degree in order to formulate corresponding countermeasures to evade the risks, and realize sustainable growth.

Abstract: Aiming at laser disturbance to IR homing anti-ship missile, laser disturbance to IR detector was researched. First, link model on laser disturbance to anti-ship missile IR detector was set up. Then laser atmospheric transmittance on the sea was deduced. 1.06μm laser atmospheric transmittance on the sea was calculated. The relationship was obtained among atmospheric transmittance and visibility and elevation. And then 10.6μm laser atmospheric transmittance curve was described. The curve is changed by visibility and propagation distance. Finally, 1.06μm laser was given as an example, the necessary laser energy which can disturb effectively anti-ship missile IR detector was calculated.

Abstract: The interesting signal is often contaminated by heavy-tailed noise that has more outliers than Gaussian noise. A robust wavelet threshold based on the minimax description length principle is derived in the ε-contaminated normal family for maximizing the entropy. Compared with classical threshold based on Gaussian assumption, the robust threshold can eliminate the heavy-tailed noise better, even if the precise value of ε is unknown, which shows its robustness. The further experiment shows that soft threshold is more suitable than hard threshold for robust wavelet threshold technique.

Abstract: At present, the existing embedded database products have high degree of specialization and dependencies of platform, not fully reflect the characteristics of embedded system. This paper provides a requirement analysis and gives a completely different from the traditional design of the database, the paper has done a lot of research in some key technologies on the design and implementation of SOC technology, this design is always used in cross platform embedded database. The SOC technology embedded in a database system in the special chip to solve problems of platform portability.

Abstract: Time delay estimation is the basis of target location of multi-sensor network, while the basic analysis of the signal is of key importance to the time delay estimation. In this paper, a time delay analysis system is designed by virtual instrument development tools. The analysis system contains: virtual oscilloscope, virtual spectrum analyzer, virtual filter and virtual time delay analyzer. Using this analysis system on a set of field collected acoustic target signal, spectrum analysis and filtering is made. Then the time delay estimation has been carried out for several sampling data segments selected by certain rules, and curve of the time delay vs. time is given. Analysis shows the main frequency of the target signal: 85Hz, 13Hz, 170Hz and 125Hz. The regular pattern of the time delay curve is consistent with the target motion. Application reveals that the system is helpful in the research of time delay estimation.

Abstract: In this paper, a new method of vibration signal analysis of coal and gangue based on Hilbert-Huang transform is presented. Empirical mode decomposition algorithm was used to decompose the original vibration signal of coal and gangue into the intrinsic modes for further extract useful information contained in response signals under complicated environment. By analyzing local Hilbert marginal spectrum and local energy spectrum of the first four intrinsic mode function components, we found the difference of coal and rock in specific frequency interval that the amplitude and energy mainly distributed at frequency interval between 100Hz and 600Hz when coal was drawn, while the amplitude and energy were more concentrated at 1000Hz or so when gangue was drawn. Furthermore, the further analysis result from marginal spectrum of each intrinsic mode function component agreed well with the conclusion above. So the extracted features with the propose approach can be served as coal and gangue interface recognition.

Abstract: This article introduces chirp spread spectrum technology (CSS for short), and location algorithm is optimized. Symmetric double-sided two way ranging technique (SDS–TWR for short) is applied to improve measurement accuracy and range. Linear frequency modulation ranging technology uses protocols combining CSMA / CA and TDMA, and adjusts dynamically transmission rate and frame length according to noise, interference and multipath to ensure optimal throughput and accurate distance information. System has anti-jamming capability and covers great distance.

Abstract: In recent years, there have been extensive studies and rapid progresses in automatic text classification, which is one of the hotspots and key techniques in the information retrieval and data mining field. Feature extraction and classification algorithm are the crucial technologies for this problem. This paper firstly proposed feature extraction algorithm based on key words, the algorithm selected key words set from special part of scientific papers, and employed mutual information to extract features. And then, proposed an improved hierarchical classification method, and realized hierarchical classification of Chinese scientific papers.