Applied Mechanics and Materials Vols. 278-280

Abstract: A solar mobile power based on single chip microcomputer (SCM) is proposed in this paper, which has the functions of charge control, power management, communication, voltage\current\temperature detection and protection. This paper takes wireless sensor as its research object, conducting experimental research in the charging\discharging character of the solar mobile power and the accuracy of its residual capacity prediction algorithm. The results show that the maximum error of the current is 4.8% during the constant current charging process, while the maximum error of the voltage is 0.05% during the constant voltage charging process. Besides, the discharging character and residual capacity prediction accuracy can also guarantee the quality of power supply.

Abstract: To solve the test problems of electronic charging machine, and to change the original test module based on artificial test. This paper described the research and implementation of a kind of electronic charging machine tester with an embedded system controlling step motor. The tester could imitate manual swiping and achieve swiping automatically. It used LCD and LED display technology, and could display the tester’s working condition and the number of swiping. The realization of this kind of tester will get rid of the original testing way of car charging machine and change the test method, meanwhile improving work efficiency.

Abstract: The pinched hysteresis loop belongs to the fingerprints of the so-called mem-systems, their well-known special cases being memristors. The memory effect of the system is determined by the area of the curve lobes which gradually decrease with increasing repeating frequency of the excitation signal. The paper describes a method for automated computation of the above areas via the commonly utilized OrCAD PSpice simulation software with the help of special measuring functions of the PROBE postprocessor. The usefulness of the method is illustrated on an example of the analysis of a TiO2 memristor.

Abstract: According to the shortage of the traditional offset line in Doherty power amplifier, a new offset line technique is proposed to match carrier amplifier with the load and to improve the performance of the Doherty amplifier. By simulation of the computer software, a higher efficiency is obtained using the new offset line comparing the two kinds of offset lines. The new offset line matching technique could be applied in the system with high linearity and low power operation.

Abstract: In order to improve the efficiency of Digital TV transmitter, we uses a new type of four-stage Doherty structure. Based on the transmission line theory and active loadpull theory, we deduce the principle of the four-stage Doherty structure, and use ADS to design a four-stage Doherty power amplifier. The simulation result shows that this four-stage Doherty PA has an efficiency of 34% at 6dB back-off (53dBm) for DVB-T OFDM 64 QAM modulated signal. The ACPR and MER obtained at 53dBm when output power are 31dBc and 28dB respectively.

Abstract: This paper firstly starts from the theory research of singular value ratio (SVR) spectrum and discusses the invalid reason of this spectrum and its improved one in some period detection. Then, on this basis, we put forward a new method utilizing delayed way to change the internal element arrangement of a fixed structure matrix to solve the invalid problem and realize reliable period detection for periodic signal. After that, we study the best number of row and column for constructing this matrix and propose the period judging principle. Finally, by contrast, the validity and superiority of the proposed method are verified in the processing of rotor system signal.

Abstract: Based on the mathematical analysis of band transmission signal coherent detection theory and mud pressure DPSK signal modulation process, by establishing the coherent detection mathematical model of mud pressure DPSK signal, this paper studies the practicability of broadband mud pressure DPSK signal coherent detection. By analyzing the noise impact on input signal parameter of demodulation system, based on probabilistic statistics theory and coherent demodulation mathematical model, the bit error rate and antinoise ability of mud pressure DPSK signal is studied. Theoretical analysis and numerical simulation indicate that, by adding arc cosine and derivation segment to basic demodulation process, the coherent demodulation effect of mud pressure DPSK signal is satisfied, but the demodulation process is more complex than conventional communication system. Theoretical analysis shows that mud pressure DPSK signal has the same theatrical bit error rate as conventional communication binary phase shift keying (2PSK) signal, but due to the difference of signal demodulation means, the reconstruction of rotary valve control pulse will be affected seriously by the derivate of vertical component of the noise within frequency band, causing that the antinoise ability of mud pressure DPSK signal demodulation system is far lower than 2PSK signal system, and numerical calculation shows that the actual bit error rate is far higher than latter; so under the condition of large carrier frequency, to obtain relative small actual bit error rate and relative larger information transmission rate, the mud pressure DPSK signal input signal-to-noise ratio should be raised as far as possible.

Abstract: Data acquisition for simulation training system can provide reliable operation data sources for system displaying, monitoring, controlling and evaluation. It takes an important role in simulation training system. This paper studies and designs one kind based on database trigger mechanism document data acquisition method. This method can guarantee real-time information collection and write data to the remote target database table in real time. It’s suitable for the data processing system of information acquisition application.

Abstract: Recommendation systems have a prevalent cold-start problem. The problem is occurred might due to new users or new items (music) are added into the system. In this paper, the meaning of the cold-start is narrowed to that the systems do not understand the new user’s preferences. Therefore, systems can not recommend the music to users. Although many recommendation systems have a solution to reduce the cold-start, e.g., general systems utilize random to select songs. The systems random select some music works to user so that systems will know the user’s preferences after they rated the music works. However, systems may cost much time to collect the necessary information when the new user is interesting in some special types of music. Therefore, if systems select various type of music initially, the user’s preferences will be extracted more quickly. That is the cold-start problem can be reduced when the types of initial recommended music are various. In our approach, we utilize SOM to select some music from clusters. According to experiment, SOM selects type of music more average than k-means and random selection. Therefore, SOM can improve the cold-start problem and increase the precision of recommendation results.

Abstract: Although traditional algorithms can led to suppressed voice in the noise, but the distortion of the voice is inevitable. An introduction is made as to the speech signal enhancement with an improved threshold method. Compared MATLAB experimental simulation on simulated platform with traditional enhanced algorithm, this paper aims to verify this method can effectively remove the noise in the signal, enhanced voice quality, improve speech intelligibility, and achieve the effect of the enhanced speech signal.