Advanced Materials Research Vols. 834-836

Abstract: Phase noise and spurious signals of local oscillator will affect the performance of short-wave receiver. The structure of receiver's front-end part based on DDS is introduced to realize a high-performance local oscillator of short-wave receiver. Then measures were taken to improve the LO's performance, including using external directly frequency multiplier as DDS' clock to improve the purity of frequency spectrum, tracking filter to degrade harmonics and gain control circuit to remain constant amplitude in the desired frequency range. At last, test results show that the above-mentioned measures improve the receiver's performance.

Abstract: Research on the mathematical model and output characteristics of a large photovoltaic array has important significance for optimal allocation and maximum power point tracking. Based on the double-diode model of photovoltaic cells, this paper deduced the mathematical model of a large photovoltaic array and made the improvement to the model and parameter optimization. According to the principle of the maximum power point matching, the large photovoltaic array MATLAB simulation mode of the improved double diode was established by use of the Newton - Ravson algorithm to determine the values of Rs and Rp. The model has the advantages of simple structure, fast operation, and the output characteristics for various light irradiation and temperature levels could be simulated exactly only by use of some parameters from photovoltaic cell production businesses. The output current data of PV module under different temperature and illumination were measured by experiment. Compared with the simulation model, it is concluded that the precision of the model in low light and high temperature condition is better than that of the single diode model, and can be applied to various types of large photovoltaic array..

Abstract: The pipeline cathodic protection monitoring was used in potential test of cathodic protection in pipeline. The test period was last 1 or 2 months or longer. the measurement accuracy and reliability of testing data are affected by testing environment and the accuracy of the instrument in some ways, so in order to meet the requirement of cathodic protection potential monitoring, it is necessary to design a cathodic protection potential acquisition system to realize the automatic monitoring of cathodic protection potential, the system was an automatic acquisition pipeline potential device used in buried steel pipeline environment. The internal circuits of the device used single chip design of low power consumption and are high precision DC voltage and AC voltage effective value measurement device all based on AVR MCU, combining hardware with software, the results show that the system realizes the automatic acquisition of buried pipeline potential and completes the indicators in China.

Abstract: Absorption coefficient is an important parameter of the absorption function of the absorption material. Traditional measurement methods of absorption coefficient are standing wave tube and reverberation which have some shortcomings. In this paper, phase of the sound pressure measured by two equal distance microphones placed in the front of the absorption material is delayed in order to attain the absorption coefficient. At the last, an experiment for one absorption material is carried out, the experiment results compare with the results of the other methods above mentioned that denotes that the theory is correct and practicable. Key words: absorption material standing wave reverberation time delaying

Abstract: In Time of Arrival (TOA) positioning technology based on base station (BS), besides the measurement error caused by mobile station (MS), Non Line Of Sight (NLOS) propagation become the main factor of the positioning error. Aiming to solve this problem especially in indoor positioning, we introduced the differential calculus method to linearize the positioning equations, and Mirror Image Method (MMI) to turn the NLOS propagation into LOS propagation, then we collected a small amount of feature point information in the positioning region which include the received TOAs at this point, feature point coordinates and BS coordinates or the mirror image coordinates of BS. In the following 3D scenario simulation, we took use of the differential calculus as well as Least Square (LS) method to get the position of the MS. Simulation results show that by using the whole mechanism, we can achieve a high positioning precision.

Abstract: The conformal coating phosphor converted light emitting diode (LED) is one of the important high power white LED. The thickness, concentration and concentration distribution of the phosphor layer has a critical influence on the LED optical performance. Previous literature mainly focus on the luminous flux of the LED. Few are involved with the relationship between the concentration and the correlated color temperature (CCT), and angular color uniformity (ACU) of LED. Based on the ray-tracing simulation, the luminous flux, CCT and ACU affected by the phosphor thickness, concentration and concentration distribution were obtained and studied. The results provide effective references for the phosphor coating process design and optical performance analysis of conformal coating LED.

Abstract: Aiming at the current maintenance of the lead-acid batteries on CDMA bases, this paper analyses the main reasons for the battery failure and puts forward the system for the remote monitoring and control of the battery. It introduces the parameters about the battery current, voltage and temperature as well as the power relay working theory. Furthermore, the remote monitoring platform is developed to monitor the battery working states in real time. With the data analyzed, the automatic control will get started to charge/discharge the battery. The system can prolong the working life of the lead-acid battery effectively and improve the battery maintenance efficiency so as to reduce the maintenance cost.

Abstract: High speed spindle is a multivariable and strong coupling complex system. In order to improve its dynamic response characteristics and control effectively, based on vector control, the high speed spindle needs to be decoupling first. Then neural network theory and BP algorithm are adopted to form a speed controller to adjust the rotational speed. In this controller, gradient searching technique is applied and the proportional and integral parameters are used as weight of neural network which is employed to adjust the corresponding control parameters. Therefore, a new model of high speed spindle is set up and simulated. The result of simulation indicates that the way combine the decoupling method and the speed controller based on neural network can track the rotational speed more accurate and promote the robustness of high speed spindle.

Abstract: A beam of Argon ion laser (λ = 488 nm and P = 40 mW) was used to irradiate some palladium deuterides with different deuteron loading ratios in a D/Pd gas-loading system (19 different loading ratios ranging from 0 to 0.77). The results showed that there was a maximum excess heat of about 287 J within an hour in the system when the loading ratio was about 0.65. This corresponds to 2.6×10³ eV/atom D or 1.7 ×10³eV/atom Pd. The results indicate that the proper ratio in the Pd lattice matching a suitable triggering power may be the key factor to excess heat production.

Abstract: A method to develop a vision system for dimension measurement of mechanical parts based on LabVIEW 2012 was proposed. The major emphasis was on how to create the sub-VI (Virtual Instrument), which could be embedded in an automatic vision measurement system, with various image processing techniques in Vision Assistant 2012. Experiment had been carried out to measure mechanical parts with this vision system, and the results showed that the method had the advantages of short program cycle, high measurement accuracy and easy to realize automation, and therefore had broad market prospects.