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Skew n-derivations on semiprime rings
Xiaowei Xu,Yang Liu,Wei Zhang 대한수학회 2013 대한수학회보 Vol.50 No.6
For a ring R with an automorphism σ, an n-additive mapping Δ: R × R × · · · × R ! R is called a skew n-derivation with respect to σ if it is always a σ-derivation of R for each argument. Namely, if n − 1 of the arguments are fixed, then Δ is a σ-derivation on the remaining argument. In this short note, from Breˇsar Theorems, we prove that a skew n-derivation (n ≥ 3) on a semiprime ring R must map into the center of R.
SKEW n-DERIVATIONS ON SEMIPRIME RINGS
Xu, Xiaowei,Liu, Yang,Zhang, Wei Korean Mathematical Society 2013 대한수학회보 Vol.50 No.6
For a ring R with an automorphism ${\sigma}$, an n-additive mapping ${\Delta}:R{\times}R{\times}{\cdots}{\times}R{\rightarrow}R$ is called a skew n-derivation with respect to ${\sigma}$ if it is always a ${\sigma}$-derivation of R for each argument. Namely, if n - 1 of the arguments are fixed, then ${\Delta}$ is a ${\sigma}$-derivation on the remaining argument. In this short note, from Bre$\check{s}$ar Theorems, we prove that a skew n-derivation ($n{\geq}3$) on a semiprime ring R must map into the center of R.
Xiaowei Xu,Liangqun Qi,Shubin jiang 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.6
In view of the bias of panel data model set can lead to misjudgment to the relationship between enterprise value and the capital structure, this article uses nonparametric method to study the relationship between them, adjusts variables in the model. The article evaluates the optimal capital structure of listed companies of the equipment manufacturing industry in our country Based on financial data from 2006 to 2013, analyzes from the Angle of enterprise value and agency cost respectively,. The results show that, The relationship between enterprise value and capital structure is inverted u-shaped, there exists a maximum asset-liability ratio in enterprise value. And the relationship between agency cost and capital structure present u-shaped roughly, there is a minimum asset-liability ratio in agency costs, there is a reasonable capital structure interval when asset-liability ratio is in range (32.87%, 58.21%).
MISFIRE FAULT DIAGNOSIS OF RANGE EXTENDER BASED ON HARMONIC ANALYSIS
Xiaowei Xu,Zhenxing Liu,Jiangdong Wu,Jiaming Xing,Xiaoqing Wang 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.1
For an Extended-Range Electric Vehicle (E-REV), the misfire failure of the range extender can result in working condition deterioration, mileage decrease, vibration and noise increase, and other adverse consequences. The relationship of the shaft instantaneous angular speed (IAS) signal and the misfire fault of the range extender was studied by harmonic analysis. Based on the theory of shafting torsional vibration, the range extender dynamics model was developed to analyze the changing trend of the shaft IAS theoretically. Then, the shaft IAS signal under different working conditions was simulated using a developed range extender rigid-flexible hybrid multi-body dynamics model. It is found that the 0.5-order harmonic phase and the amplitude of range extender IAS can be used as the characteristic parameters in misfire fault diagnosis, which has been verified by experiments on an engine bench.
An Improved Weight Optimization AAIM Method Aided by Barometric Altimeter
Xiaowei Xu,Jizhou Lai,Min Liu,Zhiming Zheng,Yuting Dai,Kai Huang 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.3
Aiming at the problem of insufficient availability in the satellite receiver autonomous integrity monitoring (RAIM) method, an improved aircraft autonomous integrity monitoring (AAIM) method aided by barometric altimeter based on weight optimization is proposed under the actual configuration of the airborne navigation system. The information of satellite navigation system and barometric altimeter is used to establish the observation equation of the integrated system. The algorithm for integrity monitoring and protection-level calculation is derived based on multiple solution separation, and a weight optimization is adopted to achieve a trade-off between position accuracy and integrity, which can improve the availability of AAIM method. The simulation experiment shows that when the number of visible stars is 5, the traditional method cannot effectively detect the satellite fault, and the positioning error is 43.65 m. The improved algorithm can effectively isolate the fault and reduce the positioning error to 0.37 m. Compared with the traditional RAIM algorithm and the Baro-aided AAIM algorithm, the proposed algorithm has a lower vertical protection threshold. Therefore, the algorithm in this paper improves the performance of satellite navigation system integrity monitoring and ensure the accuracy and reliability of the satellite navigation system.
Xiaowei Xu,Sui Li,Hongxia Wang,Nan Zhang,Zhenxing Liu 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.2
Due to the complex structure and wide excitations of range extender, the misfire and stator short-circuit coupling fault is easy to occur. Therefore, it is necessary to study the coupling fault mechanism of range extender, analyze the cause of the fault and the evolution law of fault, and diagnose the coupling fault through coupling fault characteristics ultimately. In this paper, a range extender is taken as research object. By establishing a nonlinear dynamic model and using Runge-Kutta method with variable step size, the dynamic response characteristics of system under different working conditions are analyzed to study the single fault and coupling fault mechanism. Then through the finite element analysis and practical experiments, the feasibility of coupled fault diagnosis is verified. The results show that when misfire fault and stator short-circuit fault occur at the same time, the vibration intensity of coupling fault is greater than that of single fault, and the 0.5- and 3.0-order harmonic amplitudes of horizontal vibration speed increase with the coupling fault.
Xiaowei Xu,Xueyuan Wang,Rui Zhang 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.5
The servitization of the equipment manufacturing industry is an important way for equipment manufacturing industry to adapt to the new competitive environment, and achieve industrial upgrading based on service function strengthening on value added stages along value chain. In this paper, the necessity of the servitization of the equipment manufacturing industry are analyzed in detail, and quantitative measure are used to analyze the key factors affecting servitization of the equipment manufacturing industry from external and internal two aspects. According to the influence factor analyzing results, specific methods of servitization are put forward.
Heterogeneously Integrated Thin-film Lithium Niobate Electro-optic Modulator Based on Slot Structure
Xiaowei Li,Yin Xu,Dongmei Huang,Feng Li,Bo Zhang,Yue Dong,Yi Ni 한국광학회 2022 Current Optics and Photonics Vol.6 No.3
Electro-optic modulator (EOM) takes a vital role in connecting the electric and optical fields. Here, we present a heterogeneously integrated EOM based on the lithium niobate-on-insulator (LNOI) platform. The key modulation waveguide structure is a field-enhanced slot waveguide formed by embedding silicon nanowires in a thin-film lithium niobate (LN), which is different from the previously reported LN ridge or etchless LN waveguides. Based on such slot structure, optical mode field area is reduced and enhanced electric field in the slot region can interact well with LN material with high Electro-optic (EO) coefficient. Therefore, the improvements in both aspects have positive effects on enhancing the modulation performance. From results, the corresponding EOM by adding such modulation waveguide structure achieves better performance, where the key half-wave-voltage-length product (V π L) and 3 dBEO bandwidth are 1.78 V · cm and 40 GHz under the electrode gap width of only 6 μm, respectively. Moreover, Lower V π L can also be achieved. With these characteristics, such field-enhanced waveguide structure could further promote the development of LNOI-based EOM.