Applied Mechanics and Materials Vol. 775

Abstract: This paper proposes a new step-up DC-DC converter topology with a high voltage conversion ratio for renewable system applications. The desired high voltage gain and satisfactory performance can be achieved by employing only a single power switch with simple control technique. The proposed converter can be used to step up the low voltage generated from renewable energy sources, such as solar photovoltaic modules, to the high level of the dc bus voltage, obtaining low-to-high voltage conversion ratios of approximately 30 times without adopting extremely large duty cycle. Employing the proposed converter the low input voltage (20-50Vdc) can be boosted up to the high output voltage level about 600Vdc at the dc-link bus required for the three-phase inverter feeding the three-phase motor drive system. In this paper, the proposed converter configuration with only one active power switch is presented. The operating principleincluding analysis of the steady-state performance characteristics under continuous conduction mode (CCM) operating conditions is described. In addition, the control strategy is developed in order to obtain the satisfactory output voltage regulation. Finally, simulation results are shown to demonstrate the effectiveness of the proposed converter with its control strategy to achievehigh step-up conversion ratios under different operating conditions.

Abstract: This paper mainly adopts the virtual instrument to realize the test on the accuracy of precise transmission chains, and a precise transmission testing system has been developed. The system based on the LABVIEW software can realize data acquisition, signal processing and display of results, meanwhile,it can dynamically analyze the precision of the transmission chain. The results of the actual measurements show that the testing system can accurately and rapidly measure the precision index, furthermore, it has the characteristics of high accuracy, good real-time performance, flexible operation, easy to modify the measurement program. the system can not only be used in signal measurement and analysis, but also can automatically record and store data. What is more, it can real-time display dynamic precision and transmission error curve of precise transmission chain , It is Suitable for the precision measurement and error analysis of high precision transmission chains (such as harmonic gears, planetary gears and so on) ,and has a good application value in this field.

Abstract: This paper presents the structure design and the performance testing method of a novel type of gas braking control system. Based on PDSOFT 3D design method double gas detection instrument control system has been carefully designed, effectively using the space of the case body. Using a direct acting overflow pressure reducing control technology, effectively through gas level decompression pressure were quickly and accurately is reduced to 0.7Mpa and 0.45Mpa, according to the tightness test results show, the tester can keep the pressure stability of the error is less than 0.1%. With quick joints of interlocking sealing design technology based on, settle the problem of connecting and sealing between the traction chassis brake system pneumatic hose and gas path instrument brake control pipeline, detection of gas pipeline. In the design of DC regulated power supply, the innovation to the DC voltage stabilizing circuit modular design, can effectively avoid the input voltage fluctuation on the influence of the load end, to ensure the stable operation of the independent power supply module tester. The tester can be easily used to test their performance general traction air braking system chassis in the stationary state, and can be directly used digital display reading way test data will be output directly, save the test time, improve the test efficiency.

Abstract: Shaking table is an important component in rapid detection system of microorganisms. Based on the discussion regarding the advantage and shortage of the shaking table, this paper proposed a simple, reliable, and low-cost automatic shaking table. Three mechanisms were discussed with the achievement of reciprocating motion: slide-crank mechanism, follower-cam mechanism, and incomplete gear mechanism. The three mechanisms were compared in mechanical motion pair, motion form, component design, and manufacturing process. The slide-crank mechanism was finally determined. To overcome the strong oscillation of the liquid in the test tube along a single direction, this paper improved the slider-crank mechanism, and whose trajectory was modified into an irregular circle.

Abstract: A novel growing-window recursive algorithm for stochastic system change detection is derived based on the Bayesian inference principle. Model based detectors can be formalized by two concepts in literature: (a) working in a sliding-window strategy because of time-dependent computational complexity, or (b) running in parallel, each one matched to a certain assumption on a change point. This motivates us to investigate a more refined approach which utilizes all relevant data to catch the next change point. The basic idea is to formulate a distance measure between two probabilities, one confirming the change occurrence and the other confirming no change in the system behavior. This study aims to solve the difficulty of sliding time arguments in the compared probabilities as new data are sequentially obtained. The outcome of this analysis is an algorithm that recognizes the time and magnitude of the change occurrence.

Abstract: In the process of railway out-of-gauge goods transportation, it is of great significance to guarantee the safety of railway transportation by measuring out-of-gauge goods counter accurately. This paper introduces the acquisition of out of gauge goods image using CCD technology and extracting out-of-gauge goods counter based on MATLAB operator edge detection algorithm. In order to determine the high quality edge detection operator and lay the foundation of measuring out-of-gauge goods counter, three types of operator to extract contour were compared and analyzed at the same time.

Abstract: It is of great importance to identify the location of the harmonic sources for the harmonic governance in the power system. Applied with optimal measurement placement (OMP) and harmonic state estimation (HSE), this paper presents a novel process based on PMU measurements to locate the harmonic sources in the distribution network. Considering the cost and the observability, the OMP can provide a scheme of the measurement placement with the minimum number of PMU measurements. In order to simplify the HSE equation, the measured data are converted to the form of voltage by the method proposed in this paper.By solving the HSE equation, the location and magnitude of the harmonic source are evaluated. The methodology is applied to the IEEE 33-bus system, and the obtained results are properly analyzed.

Abstract: Dual energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) are the two clinic imaging modalities available for examining bone quality. However, there is a dilemma in their selection. DXA uses a lower and safer X-ray dosage, but the produced image is two-dimensional, the information of bone spatial geometry and heterogeneous material distribution required for evaluating bone quality is missing; On the other hand, although QCT is able to capture all the required information, it has to use amuch higher X-ray dosage that may be a potentialhealth concern. Femur cross-section stiffness is an important parameter forassessing bone quality. Although itcan be determined from both DXA and QCT image, it is best computed from QCT for the reason mentioned in the above. In this study, we attempted to establish the ‘equivalence’ between DXA and QCT derived femur cross-section stiffness. If it is successful, DXA can be used in replacement of QCT in assessing bone quality. The study results showed that there indeed exist strong correlations between DXA and QCT derived femur stiffness, but they are not equivalent to each other.

Abstract: An online dynamic compensation of the pressure sensor based on simultaneous identification method of model order and parameter is proposed to identify the model of pressure sensor and set digital compensation links for the pressure sensor. While simulating, the compensation links can broaden the frequency band and improve the dynamic process of the pressure sensor. This article describes the realization of the digital dynamic compensation with DSP processor and the process of the experimental verification. The results show that the simultaneous identification method can be used in determination of model and digital compensation links for pressure sensor effectively. And DSP measurement device can complete online dynamic compensation effectively.

Abstract: A numerical method is proposed for calculating the fractional order derivative and successfully resolving the integrand singularity problem based on Zhang-Shimizu algorithm. And then a method is developed to calculate the twice nonlinear fractional derivative, numerical examples demonstrate the numerical method with high precision and good stability.