Time filter

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Zhang J.,Tianjin Polytechnic University | Yang T.,Tianjin University | Zhao C.,Tianjin Navigation Instruments Research Institute
International Journal of Grid and Utility Computing | Year: 2016

In wireless sensor networks, the energy consumption is one of the major issues. This paper proposes an event driven based adaptive routing algorithm that avoids the node energy consumption used for emergency monitoring. A cluster tree based on connected dominating set is constructed. When a new event takes place, the algorithm constructs a local topology in that region to quickly transfer the message through a cluster tree, so as to avoid a wide range of flood routing in the network. In addition, it proposes a periodical replacement strategy of the cluster head, which avoids too fast consumption of cluster head node energy. Only the cluster member nodes in a restricted vicinity will change their status. Simulation results show that the proposed approach avoids the node energy consumption used for emergency monitoring and the cluster head can evenly distribute loads, which effectively balances the energy consumption of network nodes, and thus efficiently extends the lifetime of network. Copyright © 2015 Inderscience Enterprises Ltd.

Xiao Z.-T.,Tianjin Polytechnic University | Zhao P.-P.,Tianjin Polytechnic University | Li S.-X.,Tianjin Navigation Instruments Research Institute
Zhongguo Guanxing Jishu Xuebao/Journal of Chinese Inertial Technology | Year: 2010

This paper presents a novel GPS/INS integrated navigation algorithm based on Fuzzy Adaptive Kalman Filtering. The method is mainly used in GPS/INS integrated navigation system to deal with time varied statistic of measurement noise in different working conditions. By monitoring the covariance between abstract residual and actual residual, the algorithm recursively modifies the gain coefficients of the filter so as to adaptively control the Kalman filter, and finally the optimal estimation is achieved. The experimentation results of the INS/GPS integrated navigation system indicate that the algorithm is effective and practical.

Ye F.,Harbin Engineering University | Zhang H.,Harbin Engineering University | Gu Y.,Tianjin Navigation Instruments Research Institute
Journal of Computational Information Systems | Year: 2012

On the basis of the traditional proportional fair scheduling algorithms, this paper proposes a kind of improved proportional fair resource scheduling algorithm is proposed with the purpose of improving the fairness performance of LTE system. By means of improving the scheduling opportunity of the users in the cell edge, the proposed scheduling algorithm user can effectively improve the performance of user fairness. The simulation results show that, comparing with traditional proportional fair scheduling algorithms, the proposed algorithm can achieve a higher user fairness performance. 1553-9105/Copyright © 2012 Binary Information Press.

Gao X.-Z.,Military Representative Office of Navy in Tianjin Navigation Instrument Research Institute | Jiang X.-X.,Tianjin Navigation Instruments Research Institute | Chen W.,Tianjin Navigation Instruments Research Institute | Li D.-C.,Tianjin Navigation Instruments Research Institute
Zhongguo Guanxing Jishu Xuebao/Journal of Chinese Inertial Technology | Year: 2012

For the problems of the systematic errors caused by the device errors and the unmodeled errors of accelerometers tested on centrifuge, a semi-parametric regression method in statistics is introduced into model identification of accelerometers. The semi-parametric regression model of accelerometers is established, and a least square semi-parametric regression model(LS-SPRM) method is proposed. In this method, the coefficients of error model of accelerometers are estimated by least square method, and the systematic errors are estimated by semi-parametric regression method. It takes whether the residuals are white noise as the condition to judge if there are systematic errors. In the semi-parametric estimation, a two-stage estimation method is utilized, and a cubic spline function is used to estimatte the non-parametric part. Then the method of selecting smoothing parameters is discussed. The simulation results demonstrate that the LS-SPRM method can significantly compensate the influences of the systematic errors and the unmodeled errors. Compared with those by the least square method, the standard deviations of accelerometer model identification by this algorithm are reduced by about 45% and the fit residuals are reduced by half.

Wang C.,Lanzhou City University | Zou Y.,Tianjin Navigation Instruments Research Institute | Luo X.,Lanzhou City University
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011 - Proceedings | Year: 2011

Electromagnetic measurement applies the theory of electromagnetic induction to the measurement. The tomography based on the electromagnetic measurement was proposed about a decade ago. Because of its characteristics of non-contact and noninvasion, the electromagnetic tomography is studied widely. The difficulties of the electromagnetic measurement are analyzed in this paper, and according to the different properties of measured objects in industry and medicine, we introduce the Electromagnetic Tomography used in industry and medicine. This paper presents a design strategy based on Field Programmable Gate Arrays (FPGA) which is used in the electromagnetic measurement and tomography systems. At last, the problems and trend of development about the electromagnetic measurement and tomography are discussed. © 2011 IEEE.

Zhao X.-M.,Tianjin Navigation Instruments Research Institute | Li M.-C.,Tianjin Navigation Instruments Research Institute
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2010

A three-dimensional (3-D) expression of the temperature transient model was presented for analyzing the nonreciprocal phase, rate and angular errors caused by the radial, axial and circumferential temperature transient effects in the fiber gyro coil. Compared with the traditional 2-D models only for modeling radial temperature transient effects, 3-D model significantly improved the accuracy and the prior for the thermal gradients along different directions. The 3-D equations in the coil were solved by using the finite element method. The rate and angular errors of a fiber gyro caused by different thermal excitations were obtained. The corresponding experiments of thermal excitations of fiber coil were carried out. The result gives a proof of the effectiveness of the 3-D model for predicting the thermal transient effects of the fiber coils on the performance of fiber gyros.

Teng H.-J.,Tianjin Navigation Instruments Research Institute | Wei J.-X.,Tianjin Navigation Instruments Research Institute | Ge Y.,Tianjin Navigation Instruments Research Institute
Zhongguo Guanxing Jishu Xuebao/Journal of Chinese Inertial Technology | Year: 2013

The space-level liquid floated gyroscopes are characterized by long life, high precision and high reliability. At present, the space-level mechanical gyroscope, particularly three-floated gyroscope, has the highest accuracy, the most widely application and the highest on-orbit reliability in our county. Controlling the contamination risk and ensuring the assembly cleanliness in the assembly process directly affect the life, reliability and precision of the liquid floated gyroscope. In this paper, the contamination control in assembly of space-level liquid floated gyroscopes was analyzed and studied, and the contamination-source type and its transmission way in the assembly process were identified. The corresponding contamination control strategy was formulated, and a monitoring mechanism was established. When necessary, assess the effectiveness of contamination control measures and take corrective action in time, based on the gyroscope yield, test data and contamination monitoring data analysis. The continuous improvement on assembly contamination control guarantees the assembly cleanliness of space-level floated gyroscope, ensuring the long life and high reliability of the products.

Xie J.,South China University of Technology | Deng Z.J.,South China University of Technology | Liao J.Y.,South China University of Technology | Li N.,Tianjin Navigation Instruments Research Institute | And 2 more authors.
International Journal of Machine Tools and Manufacture | Year: 2016

The precision freeform grinding depends on the on-machine truing of diamond wheel, leading to the inefficiency of grinding system. Hence, a virtual ball-end algorithm along with a fixed tool posture angle is proposed for the 5-axis grinding of glass by using a self-dressing diamond wheel. The objective is to realize the precision and mirror freeform grinding without any wheel-profile truing. First, virtual ball-end grinding, ground freeform surface and freeform errors compensation were modeled in 5-axis grinding system, respectively; then tool interference, envelope trace height, grain cutting depth and ground surface roughness were systemically investigated in connection with tool posture angle, tool sizes, grain protrusion variables, abrasive parameters and self-dressing coefficient; finally, the 5-axis grinding experiments of F-theta freeform glass lens were performed. It is shown that the virtual ball-end algorithm is valid for the 5-axis freeform grinding with a self-dressing abrasive tool. Increasing tool posture angle decreases the grain cutting depth to the critical cutting depth from brittle cutting to ductile cutting, but it increases the risk of tool interference. The mirror freeform grinding may be parameterized by material behavior, tool size and posture, grinding conditions and abrasive tool performance. On the base of virtual ball-end algorithm, the form errors compensation enhances the mirror-ground freeform accuracy by 26%. It is confirmed that the 3-μm-size diamond grinding without on-machine truing is feasible to fabricate the precision and mirror freeform glass along with the tool posture angle of 30°. © 2016 Elsevier Ltd

Liu H.-G.,Tianjin Navigation Instruments Research Institute | Chen G.,Tianjin Navigation Instruments Research Institute | Zhou C.,Tianjin Navigation Instruments Research Institute
Zhongguo Guanxing Jishu Xuebao/Journal of Chinese Inertial Technology | Year: 2013

The angular velocity matching transfer alignment can be used to accomplish the initial alignment of the missile's and the artillery's inertial system on vessel. However the result is always disturbed by angular deformations and delay. Dynamic angular deformations are regarded as errors in general since it is much smaller than static angular deformations. In this paper, the influences of three different dynamic angular deformations models and delay are discussed, and the simulation results are analyzed and verify by using dynamic angular deformations as the noise of the filter. When dynamic angular deformations are white noises, the angular velocity matching transfer alignments work well. However, when dynamic angular deformations are color noises, the errors of static angular deformations will be higher and sometimes do not convergence during the alignment time. After whitening the second-order Markov process, the transfer alignment is much better. The simulation results show that the maximum azimuth error can attain 2' when with 100 ms delay.

Zhou G.,Harbin University | Wang J.,Tianjin Navigation Instruments Research Institute | Li K.,Harbin University
Lecture Notes in Electrical Engineering | Year: 2011

The observability of the system states are the key indexes to check the convergence accuracy and convergence speed of designed Kalman filter. First of all, the error dynamic system equation and observation equation of strapdown inertial navigation system (SINS) online calibration are described in this paper, and then the system can be demonstrated to meet the law of piece-wise constant system (PWCS).Finally,the singular value of the system states based on the singlular value decomposition, which provides the necessary foundation of online calibration, are described. © 2011 Springer-Verlag.

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