A new LS+AR model with additional error correction for polar motion forecast

Polar motion depicts the slow changes in the locations of the poles due to the earth's internal instantaneous axis of rotation. The LS+AR model is recognized as one of the best models for polar motion prediction.Through statistical analysis of the time series of the LS+AR model's short-term prediction residuals,we found that there is a good correlation of model prediction residuals between adjacent terms.These indicate that the preceding model prediction residuals and experiential adjustment matrixes can be used to correct the next prediction results,thereby forming a new LS+AR model with additional error correction that applies to polar motion prediction.Simulated predictions using this new model revealed that the proposed method can improve the accuracy and reliability of polar motion prediction.In fact,the accuracies of ultra short-term and short-term predictions using the new model were equal to the international best level at present.

Routing Protocol Based on Grover’s Searching Algorithm for Mobile Ad-hoc Networks

In Mobile Ad-hoc Networks (MANETs), routing protocols directly affect various indices of network Quality of Service (QoS), so they play an important role in network performance. To address the drawbacks associated with traditional routing protocols in MANETs, such as poor anti-fading performance and slow convergence rate, for basic Dynamic Source Routing (DSR), we propose a new routing model based on Grover's searching algorithm. With this new routing model, each node maintains a node vector function, and all the nodes can obtain a node probability vector using Grover's algorithm, and then select an optimal routing according to node probability. Simulation results show that compared with DSR, this new routing protocol can effectively extend the network lifetime, as well as reduce the network delay and the number of routing hops. It can also significantly improve the anti-jamming capability of the network.

Design of an Equipotential Shielding 1000 kV Capacitor Voltage Transformer

With the increase of the operating voltage and enlargement of the size of the capacitor voltage transformer(CVT),the additional measurement error caused by stray capacitance coupling and leakage current along the polluted surface of the CVT becomes noticeable.The equipotential shielding CVT(EPSCVT)was proposed and designed by the authors to mitigate these effects.An improved conceptual design option of the EPS-CVT is presented in this paper with special references to this study to improve the shielding effect without the increase of shielding capacitance.A proposed method of non-uniform capacitance configuration can improve the shielding effect significantly without an increase of the external shielding capacitance.Based on this achievement,the potential difference and the capacitive current exchange between the internal measuring system and external shielding systems are significantly reduced.In the evaluation of the shielding effect for the influence of stray capacitance,compared with a conventional CVT with equal capacitance,EPS-CVT can reduce the measurement error by two orders of magnitude.In addition,the measurement error caused by the leakage current can also be greatly reduced,especially for the reduction of the phase angle error.Based on the improved design method,a design scheme for an engineering application is proposed which can achieve effective shielding while ensuring as good a technical performance as the existing CVT.