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OSCILLATORY BEHAVIOR OF THE SECOND-ORDER NONLINEAR NEUTRAL DIFFERENCE EQUATIONS
Zhang, Zhenguo,Dong, Wenlei,Ping, Bi 한국전산응용수학회 2001 The Korean journal of computational & applied math Vol.8 No.1
In this paper, we consider the oscillation of the second-order neutral difference equation Δ²(x<SUB>n</SUB> - px<SUB>n-r</SUB>) + q<SUB>n</SUB>f(x<SUB>n</SUB> - σ<SUB>n</SUB>) = 0 as well as the oscillatory behavior of the corresponding ordinary difference equation Δ²z<SUB>n</SUB> + q<SUB>n</SUB>f(R(n,λ)z<SUB>n</SUB>) = 0 AMS Mathematics Subject Classification : 39A10
OSCILLATORY OF UNSTABLE TYPE SECOND-ORDER NEUTRAL DIFFERENCE EQUATIONS
Zhang, Zhenguo,Ping, Bi,Dong, Wenlei 한국전산응용수학회 2002 The Korean journal of computational & applied math Vol.9 No.1
We consider the problem of oscillation and nonoscillation solutions for unstable type second-order neutral difference equation : $\Delta^2(x(n))-p(n)x(n-\tau))=q(n)x(g(n))$. (1) In this paper, we obtain some conditions for the bounded solutions of Eq(1) to be oscillatory and for the existence of the nonoscillatory solutions.
Zhang, Zhenguo,Yang, Aijun,Di, Congna 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.25 No.1
In this paper, the existence of bounded positive solution of the second-order nonlinear neutral differential equations are studied. Some new sufficient conditions are given. Furthermore, examples given show that the results here are almost sharp.
OSCILLATION CRITERIA OF SECOND ORDER NEUTRAL DIFFERENCE EQUATIONS
Zhang, Zhenguo,Lv, Xiaojing,Yu, Tian 한국전산응용수학회 2003 Journal of applied mathematics & informatics Vol.13 No.1
Some Riccati type difference inequalities are established for the second-order nonlinear difference equations with negative neutral term $\Delta$(a(n)$\Delta$(x(n) - px(n-$\tau$))) + f(n, x($\sigma$(n))) = 0 using these inequalities we obtain some oscillation criteria for the above equation.
OSCILLATION AND NONOSCILLATION OF HIGHER-ORDER DIFFERENCE EQUATIONS WITH NONLINEAR NEUTRAL TERMS
Zhenguo Zhang,Aijun Yang,Congna Di 한국수학교육학회 2007 純粹 및 應用數學 Vol.14 No.2
In this paper, the oscilation and existence of nonoscilatory solutions of odd order difference equations with nonlinear neutral terms are studied respec-tively. Some new criteria are established. Furthermore, some examples are given to illustrate the advance of our results.
Zhenguo Zhang,Houhun Li 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.3
The biology and immature stages of Epicephaha assamica Li (Lepidoptera: Gracilariidae) were investigated firstly based on the field observations and laboratory experiments, E. assamica pollinate for Glochidion assamicum (Muell. Arg.) Hook. (Phyllanthaceae) and then lay eggs in pollinated female flowers. In turn, hosts partly sacrifice seeds for larval growth and keeping some seeds for breeding, thus they form the most strictly integrated one-to-one nursery pollination mutualism. E. assamica have two generations correspondingly which are closely consistent with flowering phenology of G. assamicum, peak in March–April and September–October respectively. We investigated the benefits that each species obtains from partner. For G. assamicum, the ripening rate is 51.14%, the rate of consumed fruits is 79.52%, the average number of seeds consumed by each larva is 2.62, and the proportion of intact seeds is 68.03% that could keep the stabilization of mutualism in each population. The study first reports sex ratio in the genus Epicephala and suggests that the male-biased offspring in E. assamica can make sure that female moths have more mating opportunities. The eruciform larva bears three pairs of thoracic legs and four pairs of prolegs on abdominal segments III–V and X (caudal proleg), 11 crochets uniserial arranged in proleg. Antenne exceeds segment X in pupa. The study helps to further understand the evolutionary mechanism and driving force of coevolution in the obligate pollination mutualism between Epicephala and Glochidion.
Torque Ripple Minimization in Direct Torque Control of Brushless DC Motor
Zhenguo Li,Songfa Zhang,Shenghai Zhou,Jin-Woo Ahn 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5
This paper mainly proposes a direct torque control strategy to minimize torque ripple in brushless DC (BLDC) motor. BLDC motor has large current and torque ripple when one voltage vector applied in one cycle due to its low inductance. Hence, this paper proposed a hysteresis torque control with PWM mode to control the resultant torque. Moreover, when the direct torque control system is operating during the two-phase half-bridge 120° conduction mode, large torque ripple in commutation area appears every 120 electrical degree. Based on analyzing the root of torque ripple in detail, lookup tables of switching devices states for new half-bridge modulation mode in the positive and negative reference torque put forwarded. Finally, simulations by MATLAB software and experiment results from DSP are presented to verify the feasibility and effectiveness of the proposed strategy operating in four-quadrant operation.
Yatao Zhang,Zhenguo Ma,Wentao Dong 한국정보처리학회 2020 Journal of information processing systems Vol.16 No.2
We compared a novel encoding LempelZiv complexity (ELZC) with three common complexity algorithmsi.e., approximate entropy (ApEn), sample entropy (SampEn), and classic LempelZiv complexity (CLZC) soas to determine a satisfied complexity and its corresponding quality indices for assessing quality of multileadelectrocardiogram (ECG). First, we calculated the aforementioned algorithms on six artificial time series inorder to compare their performance in terms of discerning randomness and the inherent irregularity within timeseries. Then, for analyzing sensitivity of the algorithms to content level of different noises within the ECG, weinvestigated their change trend in five artificial synthetic noisy ECGs containing different noises at severalsignal noise ratios. Finally, three quality indices based on the ELZC of the multilead ECG were proposed toassess the quality of 862 real 12lead ECGs from the MIT databases. The results showed the ELZC coulddiscern randomness and the inherent irregularity within six artificial time series, and also reflect content levelof different noises within five artificial synthetic ECGs. The results indicated the AUCs of three quality indicesof the ELZC had statistical significance (>0.500). The ELZC and its corresponding three indices were moresuitable for multilead ECG quality assessment than the other three algorithms.