It is possible to carry out PD location using the time difference of PD pulses received by a UHF antenna array. In practical applications, the electromagnetic interference within the substation will pollute these rece...
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ISBN:
(纸本)9781467310192;9781467310185
It is possible to carry out PD location using the time difference of PD pulses received by a UHF antenna array. In practical applications, the electromagnetic interference within the substation will pollute these received signals and make it difficult to calculate the time difference of the PD pulses, which, thus, reduces the reliability of the PD source locating. Based on the segmented processing technology, an adaptive Wavelet de-noising method is proposed in this paper. Considering that the level and the time-frequency characteristic of the background noise differ little in microsecond time period of sampling, each waveform acquired by PD detecting system are divided into two sections, the one without PD pulse is used for the calculation of the wavelet coefficients which are used to estimate the de-noising thresholds of the signal. The influence of this adaptive wavelet de-noising process on the PD pulse time delay calculation is analyzed in details. The results of simulation and application show that this method can suppress noise effectively and extract the PD pulse accurately, which contribute to the reliability of the PD source locating.
Measurement error occurs if the requirements of undistorted measurements cannot be satisfied by dynamic component characteristics of the sensor. Amplified time constant and longer thermal response time of armored ther...
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Measurement error occurs if the requirements of undistorted measurements cannot be satisfied by dynamic component characteristics of the sensor. Amplified time constant and longer thermal response time of armored thermocouple is caused by its additional protective cover structure and the inherent thermal inertia of the internal temperature measuring element. Therefore, there is hysteresis dynamic characteristic in actual measurement of sensor. This paper proposes an accurate compensation of armored thermocouple based on fireworks algorithm that balances the contradiction between the accuracy of the existing solution and the complexity of the solution, corrects the measured thermocouple temperature signal. Weight factor is innovatively introduced to design the fitness function of fireworks algorithm, and the iterative process is sectionally executed that achieves the improvement of time constant and thermal response time of armored thermocouple. Finally, results are given in the simulation section. Dynamic compensation time is reduced from 537ms to 130ms, which is 75.79 lower than before compensation result. Moreover, the thermal response time is reduced from 345ms to 110ms, which is 68.16 lower than the before compensation result. From the experimental results, we can observe that the proposed method in this paper can broaden the working bandwidth of the thermocouple sensor through establishing dynamic mathematical model of thermocouple. After compensation, the dynamic characteristics of armored thermocouple are close to bare bead thermocouple without protective sleeve. The proposed method can replace easily damaged bare bead thermocouple to realize accurate measurement in harsh temperature measurement environments without need frequent replacement, which also improves economic benefits.
Developing models of the dynamic and complex patterns of information processing that take place during behavior is a major thrust of systems neuroscience. An underlying assumption of many models is that the same set o...
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Developing models of the dynamic and complex patterns of information processing that take place during behavior is a major thrust of systems neuroscience. An underlying assumption of many models is that the same set of rules applies across different conditions. This has been the case for directional tuning during volitional movement;a single cosine function has been remarkably robust for describing the encoding of movement direction in different types of neurons, in many locations of the nervous system, and even across species. However, detailed examination of the tuning time course in motor cortex suggests that direction coding may be labile. Here, we show that there are discrete time epochs within single reaches, between which individual neurons change their tuning. Our findings suggest that motor cortical activity patterns may reflect consistent changes in the state of the control system during center- out reaching. These transitions are likely linked to different behavioral components, suggesting that the task defines changes in the operational structure of the control system.
Bivariate and trivariate functions for interpolation from scattered data are derived. They are constructed by explicit minimization of a general smoothness functional, and they include a tension parameter that control...
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Bivariate and trivariate functions for interpolation from scattered data are derived. They are constructed by explicit minimization of a general smoothness functional, and they include a tension parameter that controls the character of the interpolation function (e.g., for bivariate case the surface can be tuned from a ''membrane'' to a ''thin steel plate''). Tension can be applied also in a chosen direction, for modeling of phenomena with a simple type of anisotropy. The functions have regular derivatives of all orders everywhere. This makes them suitable for analysis of surface geometry and for direct application in models where derivatives are necessary. For processing of large datasets (thousands of data points), which are now common in geosciences, a segmentation algorithm with a flexible size of overlapping neighborhood is presented. Simple examples demonstrating flexibility and accuracy of the functions are presented.
Sparse Matrix-Vector multiplication (SpMV) is one of the most significant yet challenging issues in computational science area. It is a memory-bound application whose performance mostly depends on the input matrix and...
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ISBN:
(纸本)9780769545769
Sparse Matrix-Vector multiplication (SpMV) is one of the most significant yet challenging issues in computational science area. It is a memory-bound application whose performance mostly depends on the input matrix and the underlying architecture. Many researchers have paid more attentions on exploring a variety of optimization techniques to SpMV. One of the most promising respects is how to adapt the storage format to satisfy the underlying architecture. Alterative storage formats can largely lessen memory pressure, however, the computational resources are often underutilized. Therefore, a new storage format, which is called Compressed Sparse Row with segmented Interleave Combination (SIC), is proposed. Stemming from Compressed Sparse Row format (CSR), SIC format employs an interleave combination pattern that combines certain amount of CSR rows to form a new SIC row. In order to further improve performance, segmented processing is also brought in. According to the empirical data, we also develop an automatic SIC-based SpMV suitable for all the matrices. Experimental results show that our approach outperforms the NVIDIA CSR vector kernel, achieving up to 12.6x speedup. It also demonstrates a comparable performance with the Hybrid format, even with the highest 2.89x speedup.
Through the research of domestic and international aviation engine seal pieces, this paper have described the structure and technological design of electrical discharge grinding honeycomb torus. Based on experimental ...
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ISBN:
(纸本)9783037853696
Through the research of domestic and international aviation engine seal pieces, this paper have described the structure and technological design of electrical discharge grinding honeycomb torus. Based on experimental analysis of processing precision and processing efficiency under different electrical parameters, machining sections were designed according to the processing requirements of different parts. The results indicate that the machining precision and efficiency can be enhanced greatly.
This paper focuses on ranging problem of Zigbee-based positioning systems,and takes into account of both RSSI(Received Signal Strength Indication) and LQI(Link Quality Indicator) which are the most two important facto...
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ISBN:
(纸本)9781509009107
This paper focuses on ranging problem of Zigbee-based positioning systems,and takes into account of both RSSI(Received Signal Strength Indication) and LQI(Link Quality Indicator) which are the most two important factors of ***,the values of RSSI and LQI are analyzed,***,the polynomial models of both factors are derived by data fitting ***,RSSI and LQI are processed by segment *** show that polynomial modeling and segmented processing can improve the ranging accuracy.
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