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Copyright of Journal of South China Normal University (Natural Science Edition) / Huanan Shifan Daxue Xuebao (Ziran Kexue Ban) is the property of Journal of South China Normal University (Natural Science Edition) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the middle and later stages of shale gas production, the output declines and the pressure of the gas well decreases. In order to ensure smooth transmission of the product gas, the gas compressor is needed to boost production. Because the shale gas has more particulate impurities than conventional gas, if the impurities are not separation incompletely and go into the downstream, it will cause compressor damage even shut down, which will affect the shale gas production and gathering process, causing huge economic losses. As the last guarantee before shale gas entering the supercharger, the separation efficiency of filter separator is very important. But there are few studies on separation efficiency of horizontal filter separator by numerical calculation method. In this paper, FLUENT software is used for numerical simulation of the horizontal filter separator, and the flow field in the equipment is researched and analyzed. The calculation results show that the filter barrel of horizontal separator can effectively separate solid and liquid particles/ impurities. The separation efficiency is high when the liquid particle size is larger than 60μm and the solid particle size is larger than 30 μm, The overall separation efficiency can reach more than 96% . This method can effectively protect the the compressor lever, optimize the shale gas gathering and transportation technology, and ensure the safe operation of shale gas field. [ABSTRACT FROM AUTHOR]

On the practical issues such as accumulative state estimation errors caused by the inaccurate battery model， and time-varying and unknown noise statistical characteristics， a state co-estimation algorithm for Li-ion power batteries based on adaptive unscented Kalman filter (UKF) framework is proposed. During the iteration process， the measurement equation called by unscented transform (UT) each time is quasi-linearized， which could greatly reduce the computational complexity. The statistical characteristic parameters of unknown noises can be estimated by introducing Sage-Husa adaptive estimation method with forgetting factor， which could improve the adaptive fault tolerance of UKF estimation algorithm. If the divergence trend occurs in the filtering process， the error covariance will be penalized by employing adaptive attenuation factor to prevent the divergence of the filter， accordingly guaranteeing the numerical stability of filtering process. By employing co-estimation strategy， the inner ohmic resistance of the 1st-order Thevenin battery model， which could characterize the state of health (SOH) indirectly， can be estimated and adjusted in real time， and therefore a high-precision estimation of the state of charge (SOC) is able to be obtained owing to the accuracy of the battery model during the process of dynamic charge-discharge cycling tests. The comparative experimental results verify the feasibility and effectiveness of the adaptive co-estimation algorithm. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Frictionless magnetic bearings can contribute to modern agricultural equipment, such as pump, fan and blast, thereby to achieve high efficiency, energy-saving and long-term reliable operation. But magnetic bearings are confined to the configuration and price of position sensors. In the recent years, the self-sensing and sensor less mode have been developed to extend the application of the magnetic bearings. Most previous studies are focused on the estimation algorithms, such as the state observer approach and parameter estimation approach. Moreover, the extra phase-shift is introduced by the estimator which consists of the analogue filter or FIR or more complex mathematic algorithm. The self-sensing path turns complex and longer due to the fundmental ripple needs to be extracted, amplified and filtered. Therefore, the key research target of this paper is the operation of position estimation. An absolute mathermatical approach was proposed to extract the rotor positon using the zero ripple characteristic based on the cosine-function of coil current. A self-sensing algorithm based on SS-DCE (Synchronous-Sampling-based Discrete Current Estimator) can be used to remove the extra phase that introduced by the analog or digital filters of the sensing path. Synchronous-sampling technique was used to sample the coil working current in the estimator due to PWM switching harmonics without the discrete current. Moreover, the phase shift can be minimized in SS-DCE scheme because the filters of amplitude demodulation have been eliminated, and the configure of AMBs are simplified. The numerical results of SS-DCE were also compare with that of the digital filtering amplitude demodulation approach(DFAdM). The test results of the position estimators showed that the optimal performances can be obtained, when the switching frequency and synchronous sampling frequency are 2 kHz, control frequency is 50 Hz, sampling frequency of DFAdM is 100 kHz, and some electrical conditions as the bias current 3.0 A, nominal inductance 13.2 mH and power supply 50 V. The SS-DCE was also verified by the simulation in 1-DOF AMBs. The static performance evalution was performed on the proposed estimator, indicating that the precision of SS-DCE was about 2.72%, and the absolute error was 5.43 μm in the position range of 50-250 μm. The precision of DFAdM estimator was 4.85% and the absolute error was 9.71 μm. Frequency response analysis was used to evaluate the dynamics performance in open loop state, indicating 158° phase margin at the eigen frequency 19.26Hz. Moreover, a rig of self-sensing AMBs was setup with TMS320F2812, LEM HX-05, PM10CJS060 and micro-positioning platform. The precision of SS-DCE was about 2.53% referring to eddy current sensor HZ-891. SS-DCE-based rotor showed good stability, rapid convergence and acceptable overshot under pulse disturbances that applied through a direct knock on the truss by a rubber hammer. The proposed approach can provide a direct guidance for the active control of magnetic levitation, magnetic damper and other engineering fields. The influence of PWM duty-cycle and low SNR on magnetic bearings can be performed in the near future research works, thereby to enhance the application of magnetic bearings for modern agriculture. [ABSTRACT FROM AUTHOR]

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As an important part of streamflow and water cycle in a watershed, base flow can not only provide reliable water supply but also maintain healthy watershed ecologically and environmentally. It is of great significance to divide the base flow accurately from the measured streamflow and to analyze its variations for understanding the dynamics of base flow changes and managing water resources. We used the measured daily streamflow data from Daning Hydrological Station of Xinshui River Basin (3992 km2) located on the Loess Plateau of northern China, climate data measured by meteorological stations and raingauge stations located within and in the vicinity of the basin from 1955 to 2015 and the GIMMS-NDVI data to explore the dynamic changes of base flow. Base flow partitioning was conducted by using digital filtering method (3 times, α=0.925) from the daily streamflow data. Mann-Kendall test, Pettitt test, wavelet analysis and Hurst test were performed to explore the base flow changes in the aspects of trend, turning point, periodic behavior, and sustainability at annual scales. Averaged annual base flow from the basin was 45 million m3 and the base flow index (BFI) was 0.368 between 1955 and 2015. There were significant decreasing trends for yearly base flow (P<0.01), with the turning points occurring in the year of 1985. In addition, a 27- year periodical cycle was observed for annual base flow. It was predicted that the annual base flow will be further reduced in the future as indicated by a positive correlation between historical change and the future regime (H>0.50). Double mass analysis indicated that climate variability and human activities have contributed to a significant decrease in base flow. Precipitation was the major climate factor rather than temperature, which caused the decrease of base flow. The base flow is divided into three stages by the double mass curve method. Human activities affected the base flow by changing vegetation coverage, exploiting groundwater, mining coals and taking measures in soil and water conservation. Compared with the first stage, the proportion of precipitation and human activities in the second and third stages was 25.89%, 74.11% and 0.37% , 99.63% , respectively. There has been an increased impact of human activities on the decreased base flow since the beginning of the 21st century. [ABSTRACT FROM AUTHOR]

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There is need to develop a portable experimental platform for digital signal processing. In order to solve this problem, using DSP ( Digital Signal Processor) + FPGA ( Field Programmable Gate Array) as the hardware platform, a low-cost, portable digital signal processing experimental system is designed. Digital signal processor TMS320VC5509A is used as data processing core. FPGA is applied to control USB, ADC, DAC and the other peripheral devices, so that the experimental system can communicate with the PC and complete conversion between analog and digital signals. Besides, the platform can also implement the classical digital signal processing algorithms, such as spectral analysis, digital filter design, etc. Hardware debug shows that the platform can generate the basic signal for digital signal processing, and it can implement the basic experimental content for DSP course. The experimental platform can greatly enhance intuitive of the digital signal processing course. [ABSTRACT FROM AUTHOR]

In order to solve the problem of big difference between simulation process and actual application process this paper takes the signal filtering in electrical circuit system as an example, to present a design method of digital filtering system. Using relevant modules provided by the software of SIMULINK/SIMSCAPE, some electrical circuits are built, and combing some programming skill, triggered subsystem from SIMULINK modules is used to simulate the process of periodical sampling, periodic calculation of difference equation. Furthermore, relevant programming idea is introduced by the implement of a first order low pass filter. Finally, simulation results show the efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

To solve the problem that the existing affine interest point detection algorithms cannot directly determine the characteristic scale for interest point, this paper proposed an invariant interest point detector based on Gabor multiscale-space. Firstly, this algorithm built the Gabor multiscale-space representation by smoothing the image with a series of Gabor filters. Secondly, it used the maxima criterion to detect the interest points and determine the characteristic scale. Finally, it described the local structure shape of interest point by the second moment matrix. The experimental data demonstrate that the proposed detector obtains the best performance under image blur and JPEG compression in terms of repeatability and matching score, compared to other detectors, such as Hessian-Affine and MSER et al, and then it is an effective interest point detection algorithm with determining the characteristic scale directly. [ABSTRACT FROM AUTHOR]

The paper reveals the effects of the group delay in a digital filter on the stability of an active flutter suppression system for a 2 dimensional airfoil section. The wind tunnel tests show that the active flutter suppression system becomes unstable at very slow flow speed if the group delay of the digital filter is long enough. In the wind tunnel tests of flutter suppression, the flutter amplitude under control often decreases at first as expected, and then the other self--excited vibration with lower frequency and moderated amplitude appears. The paper well explains such a phenomenon through a combined theoretical and numerical study. Both wind tunnel tests and numerical simulations demonstrate that the group delay greatly affects the above unstable motion, and that both the amplitude and frequency of the new self-excited vibration will increase with the group delay. [ABSTRACT FROM AUTHOR]

A new active control strategy for suppressing unbalanced vibration of grinding electric spindle-tool system is proposed to effectively control unbalanced vibration caused by mass unbalance of electric spindle-tool system. First, the winding arrangement and the induction principle of electric spindle with two windings and the radial control force model were investigated. The dynamic model of flexible electric spindle-tool with two induction windings was established by Finite Element Method and the FBLMS adaptive digital filter control algorithm was investigated. The test system was designed. By using FEM the coefficients of the control force and unbalanced magnetic pull were determined. The vibration control effect of the tool was studied by comparing the classic PID and FBLMS adaptive filter controller. The results show that the FBLMS adaptive digital filter controller has a better control effect on suppressing the unbalanced vibration of electric spindle-tool system. [ABSTRACT FROM AUTHOR]

In terms of the given ESA power spectral density (PSD) function characteristics, a FIR digit filter was designed based on finite unit impulse response. The filter amplitude-phase characteristics that completely met the conditions of given power spectral characteristics were obtained by changing parameters of FIR digit filter. The random vibration time signal was generated with the white noise as input of the filter. Furthermore, autoregressive parameter model was used to estimate and validate the power spectrum of obtained time signal. The results show that the error between two spectral curves are in the range of permits, and the random vibration time signal obtained using presented method could completely meet the requirements of simulation and test. [ABSTRACT FROM AUTHOR]

To increase the computation efficiency of multi-scale retinex method (MSR) in image enhancement, in which the Gaussian convolution has to be used for several times, especially when large scale Gaussian convolution template is used to get the low-frequency information of image, the convolution template is simplified as mean template because the Gaussian template of large scale Gaussian convolution has the property of mean template. Furthermore, a filter window irrelevant mean filtering algorithm is proposed to fulfill and speed up the filtering process. It employs an array s to storage each column pixel value of current filtering rows and consequently reduces the redundant calculation. Taking the 640 x 640 color image as an example, the processing time is only 0.0867 s and it is 723 times faster than original MSR method. It can be seen from the analysis of experiment that the new proposed method can greatly improve the computing efficiency and fulfill the image enhancement remarkably. [ABSTRACT FROM AUTHOR]

To explore the applicability of single-negative materials pair (SNGP) in microwave devices, we established an equivalent transmission line model of reflection-typed band-stop filters based on SNGP. Its working principles and the design method were studied, and then the simulation on its performances was carried out. Results show that the filters perform well in a certain frequency range, which verifies that the method is feasible. [ABSTRACT FROM AUTHOR]

The group delay of digital filters induced instability of a controlled-double pendulum was discussed, and then a discrete delayed linear quadratic controller was used to suppress the instability. First, the dynamic model of the double-pendulum on a moving cart was established and the free-decaying vibration of the system was measured. It was found that the settling time of the free system was very long, and hence, an active control was needed to shorten the settling time. Then, the effects of digital filters on the stability of the system under the linear quadratic control were discussed, where the Butterworth low pass digital filters were used to remove the heavy noise embedded in the control input signal. The conclusion of this re- search is that if the filter parameters are properly selected, the digital filters can not only enhance the performance of control system, but also reduce the cost of energy. However, when the specifications of the filters are set too high, the group delay will exceed the critical value and cause the instability of the closed loop system. The delay controls based on state transform are suitable for the dynamic systems involving digital filters because the group delay of a digital filter can be completely determined by its frequency response of phase and can be estimated accurately beforehand. At the last section of the paper, therefore, a newly proposed discrete delayed linear quadratic controller is represented to suppress the group delay induced instability of the double pendulum. [ABSTRACT FROM AUTHOR]

To investigate the method to obtain the real-time longitudinal acceleration based on its velocity, vehicle acceleration is obtained through the velocity filtering, differential, and then filtering. Power spectrum analysis of velocity and acceleration is discussed and its Fir lowpass digital filters are designed with Fdatool box in the Matlab development environment. A kind of algorithm fitted for real-time use by a vehicle is developed and its application in microcomputer is discussed. The experimental results revealed that the algorithm is of good real-time and high precision. [ABSTRACT FROM AUTHOR]