Applied Mechanics and Materials Vols. 556-562

Abstract: The intermediate frequency signal, which is generated by down conversion of radar transmission pulse, is settled as square wave through the signal processing circuit; in N cycle of the unknown square wave of this frequency, the frequency measurement circuit with counting down method uses the counter and the time-sequence control circuit consisting of TTL integrated circuit, such as F161 and LS221, to count the standard pulse exported by homothermal crystal with high stability and then load the result in single chip in order to obtain the frequency measuring result. This frequency measuring circuits, a digital frequency measurement module, can rapidly and timely survey the transmission frequency during the constant radar transmission pulse and has been successfully applied in a self-adaption frequency control system of meter wave warning radar.

Abstract: In order to detect optical fiber submarine cable effectively, based on magnetic anomaly detection, the article presents a method for calculating magnetic field of central tube and layer stranded submarine cable by modeling. SQUID proved can be applied in the passive magnetic detection of optical fiber submarine cable.

Abstract: Accuracy and stability is crucial for dynamic object tracking. Considering the scale invariance, rotational invariance and strong anti-jamming capability of KAZE features, a method of dynamic object tracking based on KAZE features and particle filter is proposed. This method obtains the global color features of the dynamic object appearance and extracts its local KAZE features to construct the object model first, and then performs dynamic tracking by particle filter. Experimental results demonstrate the accuracy and stability of the proposed method.

Abstract: Micro-Doppler is a unique feature of radar target, and has been applied to target recognition of ISAR widely, but it can also destroy the quality of the target image at the same time. So a novel jamming method of false target base on Micro-Doppler modulation is presented in the paper. The phase of captured radar transmitting signal is been modulated, which can generate false Micro-Doppler features. The micro-Doppler imaging model of the rotating target is analyzed, and the jamming model based on Micro-Motion modulation is given. Finally, the simulation of jamming experiment is carried out. The results of simulation prove the method is corrective and effective.

Abstract: Wireless Networks suffer from many constraints including wireless communication channel, internal and external attacks, security becomes the main concern to deal with such kind of networks. Therefore, an intrusion detection system (IDS) is required that monitors the network, detects misbehavior or anomalies and notifies other nodes in the network to avoid or punish the misbehaving nodes. This paper describes the simple method to detect the intruder in wireless communication system based on physical layer characteristics. Channel prediction method is used in receiver part to predict the transmission channel for the next time slot. Then, in the next time slot the result is compared with the actual value of channel from the channel estimation. Number of detection and false alarm ratio is measured as performance matrices of the simulation. Based on simulation result, the proposed intrusion detection system give high detection ratio and low false alarm ratio for given threshold.

Abstract: Obstructive sleep apnea syndrome is a sleep-related breathing disorder that is caused by obstruction of the upper airway. In this research, we explore a computer-aided diagnosis system with portable ECG equipment and tri-accelerometer (x, y, and z-axes) that can automatically analyze biosignals and test for OSA. We developed an approach to record ECG signals and abdominal movements induced by breathing by affixing ECG-enabled electrodes onto a triaxial accelerometer. With the two signals simultaneously measured, the apnea data obtained would be more accurate, relative to cases where a single signal is measured. This would be helpful in diagnosing OSA.

Abstract: The grout behind the lining segments have a powerful influence on the long-term basis in shield tunnel construction in gravel sand and round gravel layers. Grouting layer detection in the shield construction is important. Two aspects are usually be used to evaluate the effectiveness of the grout treatment, one is the thickness of the Grouting layer and the other is to determine the presence and distribution of any damage in grouting layer. This study reports on the applications of the ground penetrating radar (GPR) and associated work carried out on Nanchang Metro line 1, Jiangxi province of China. After raw data preprocessing the results of the radar image are used to evaluate the thickness and hidden trouble of the grout layer automatically.

Abstract: A fault location method for HVDC (High Voltage Direct Current) transmission lines is proposed in this paper, using voltages and currents measured at two terminals of dc lines in time domain. Fault traveling waves propagate from the fault point to both terminals along the faulted line. The position that the traveling wave head arrives at some moment after the fault can be used to calculate the fault location. To determine the arrival positions of traveling wave head at each time indirectly, propagation characteristic curves of traveling wave heads at local and the remote terminals are calculated with distribution currents using the stationary wavelet transform. The accuracy of fault location will not be affected by transition resistance and fault position. Simulation results show that the presented fault location method can achieve quick and accurate fault location on the whole line under probable operation modes of a bipolar HVDC transmission system.

Abstract: Supraventricular tachycardia (SVT) is the most common arrhythmia and can be found in not only heart disease patients, but also healthy persons. However, the occurrence of SVT in heart disease patients implies that the potential of the heart diseases worsening, and it causes cardiac arrest when it evolves into ventricular tachycardia or the ventricular fibrillation. Therefore, the detection of SVT arrhythmia, as a first stage, has significant implications for the prevention of cardiac arrests. In this paper, we propose the automatic diagnosis system for cardiac arrhythmias detection with great accuracy. To validate the algorithm, SVT and normal sinus rhythm are classified by the proposed algorithm.

Abstract: Road scene understanding is critical for driving assistance systems and autonomous land vehicles. The main function of road scene understanding is robustly detecting useful visual objects existing in a road scene. A zebra crossing is a typical pedestrian crossing used in many countries around the world. When detecting a zebra crossing, an autonomous lane vehicle is normally required to automatically slow down its speed and to trigger a path-planning strategy for passing the zebra crossing. Also, most of driving assistance systems can send an early-warning signal to remind drivers to be more careful. This paper proposes a robust zebra-crossing detection algorithm for autonomous land vehicles and driving assistance systems. Firstly, an inverse perspective map is generated by utilizing camera calibration parameters to obtain a bird-eye view road image. Secondly, a course-to-fine detection process is applied to obtain a candidate zebra-crossing region and finally a true zebra-crossing region is recognized by combining appearance and shape features. Experiments on several kinds of real road videos which also include several challenge scenes demonstrate the effectiveness and efficiency of the proposed method.