Applied Mechanics and Materials Vols. 716-717

Abstract: A multi-symbol phase modulation format, the 8 phase shift keying (8PSK) with 50% return-to-zero (RZ) clock, is proposed and demonstrated in this scheme for 30-Gb/s optical access downlink transmission applications using phase equalization technique in MSPE. RZ-8PSK optical signals are generated by cascading three phase modulators and a dual-arm Mach-Zehnder modulator. Superimposed 50% RZ clock is extracted and recovered for achieving access restoration. The result show the reception performance of 50% RZ-8PSK signals with phase equalization after transmission over SMF-28 is good.

Abstract: Due to the lack of data about special windy or rainy day weather and the abnormal change characteristic of load, this paper proposes a new sensitivity analysis method between load and meteorological. Firstly, a method is put forward to select the factors affecting the load based on grey theory to calculate the correlation coefficient. Secondly, the multiple linear regression relationship between load and weather according to the meteorological conditions in different intervals is built to get more accurate sensitivity between load and meteorological factors. Finally, an example is used to reveal the law of load changing with weather in Haikou power grid. The result shows that the proposed method has a practical reference value for improving power grid load forecast accuracy and operation safety in the typhoon and other special weather conditions.

Abstract: Droplet mobility actuated by surface acoustic wave (SAW) was demonstrated in this paper. On the surface of the LiNBO₃ substrate, pairs of copper inter-digital transducer (IDT) were fabricated to generate Rayleigh wave at different radio frequency (RF) voltages. The various droplet motions, such as mixing, flowing and atomization were analyzed by adjusting pulse frequency and input power. The experimental results demonstrated that the SAW could function as an atomizer when the input power was higher than 25W. Based on fundamental experiments, a novel driving curve for micro droplets under different driving power was obtained as well.

Abstract: The focus law and acoustic field computation method about circular arc linear phased array have been discussed in the paper. Acoustic field of transducers is given by the use of the coordinate transformation and an approximation with rectangle element instead of circular arc element, and was calculated using Rayleigh-Sommerfeld Integral.

Abstract: Simulation-based performance degradation prognostics should firstly obtain the judgment criterion to predict degradation failure, how systems or its components degenerate, and then how to display effect of degradation process on performance. In this paper, we presented a model-based performance degradation prognostic method to address this problem. For Electro-Hydraulic servo valve case, it has strict demands on performance. Degradation of the valve is propagated forward in time and influence on performance output. The proposed degradation prognostics method is illustrated through performing comprehensive simulation experiments.

Abstract: Due to the complexity in the process of the welding, the welding parameters selection and reasonable matching will influence the quality of the power battery joints. There are not specific mathematical models between the welding parameter and the welding quality in the current period and the selection of the welding parameters is only depended on experience. In this paper, the orthogonal test is conducted on the main technological parameter of the welding of power battery packs and the optimal combination of parameters is gained after the analysis of the results of the test, which promotes the quality of the spot welding of power battery packs in series connection and in parallel connection.

Abstract: In the construction of UHVDC power line in China, the national standard of reradiation interference protecting distance between UHVDC power line and receiving station of AM broadcasting needs to be renewed. In this paper, the wire-surface simulation model is used to calculate the interference. In the model, steel tower is represented as surface model, ground wire is represented as wire model, and the whole model is excitated by vertical polarization plane wave. For the deficiency of traditional solution method of protecting distance calculation, a new method is proposed. It is recommended that the whole work frequency band of receiving station should be calculated to determine the space interval which has actual protecting distance. Then the interval is gradually narrowed with dichotomy method until the interval size is within allowable value. With the first-grade receiving station of AM broadcasting as example, the reradiation interference protecting distance from UHVDC power line and station is calculated..

Abstract: Specific to the demand for the actual operation, this paper calculates short-term failure rates of various types of elements by adopting improved conditions dependent model: temperature-dependent element aging failure model, weather-dependent occasional failure model, current-dependent overload protection model, and processes a short-term reliability assessment by forward failure diffusion algorithm. Example analysis is simulated by 11kV distribution network of IEEE RBTS Bus-2 system to prove the reliability assessment model, the reliability assessment process are effective and provide on-site operation and maintenance personnel with guidance for decision making in the short-term scheduling and online operation.

Abstract: Due to a variety of electrical equipment using, the grid power quality severely polluted. For current harmonic signal is generated in hoist converter, the methods is proposed based on Hilbert-Huang Transform (HHT) to detect current harmonic signal and improved Active Power Filter (APF). The simulation mode is established by MATLAB/Simulink software about shunt APF+SPWM inverter hybrid active filter device for harmonic motion detection and suppression simulation. The results show that the harmonic of hoist converter can be detected by this design method real-time and the harmonic can also be suppressed validly.

Abstract: High-voltage transmission line corona and sparking will bring television interference (TVI). Study has been seldom executed about active TVI from HV transmission line, and much less research on UHV AC lines. Based on present literatures, this paper brings forward test method of TVI from HV transmission line. Near straight span and tension tower of Chinese UHV AC Pilot Demonstration Project, several tests about TV picture, TVI field strength, the television signal field strength before and after lines energized, has been carried out in good weather. According to observation, interference characteristics to TV picture has been analyzed. Results indicate that, with increasing distance from the outer phase, UHV single circuit TVI field strength in fine weather attenuates negative exponentially. This paper illustrates it is questionable to use CISPR quasi-peak value for assessment of interference on TV picture caused by UHV transmission line corona and sparking noise.