GLOBAL CONVERGENCE OF A MODIFIED BFGS-TYPE METHOD FOR UNCONSTRAINED NON-CONVEX MINIMIZATION

Guo, Qiang,Liu, Jian-Guo 한국전산응용수학회 2007 Journal of applied mathematics & informatics Vol.24 No.1

To the unconstrained programme of non-convex function, this article give a modified BFGS algorithm associated with the general line search model. The idea of the algorithm is to modify the approximate Hessian matrix for obtaining the descent direction and guaranteeing the efficacious of the new quasi-Newton iteration equation $B_{k+1}s_k=y^*_k,\;where\;y^*_k$ is the sum of $y_k\;and\;A_ks_k,\;and\;A_k$ is some matrix. The global convergence properties of the algorithm associating with the general form of line search is proved.

Recognition of Radar Emitter Signals Based on SVD and AF Main Ridge Slice

Qiang Guo,Pulong Nan,Xiaoyu Zhang,Yuning Zhao,Jian Wan 한국통신학회 2015 Journal of communications and networks Vol.17 No.5

Recognition of radar emitter signals is one of core elements in radar reconnaissance systems. A novel method based on singular value decomposition (SVD) and themain ridge slice of ambiguity function (AF) is presented for attaining a higher correct recognition rate of radar emitter signals in case of low signal-tonoise ratio. This method calculates the AF of the sorted signal and ascertains the main ridge slice envelope. To improve the recognition performance, SVD is employed to eliminate the influence of noise on the main ridge slice envelope. The rotation angle and symmetric Holder coefficients of the main ridge slice envelope are extracted as the elements of the feature vector. And kernel fuzzy cmeans clustering is adopted to analyze the feature vector and classify different types of radar signals. Simulation results indicate that the feature vector extracted by the proposed method has satisfactory aggregation within class, separability between classes, and stability. Compared to existing methods, the proposed feature recognition method can achieve a higher correct recognition rate.

Method for Feature Extraction of Radar Full Pulses Based on EMD and Chaos Detection

Qiang Guo,Pulong Nan 한국통신학회 2014 Journal of communications and networks Vol.16 No.1

A novel method for extracting frequency slippage signalfrom radar full pulse sequence is presented. For the radar fullpulse sequence received by radar interception receiver, radio frequency(RF) and time of arrival (TOA) of all pulses constitute atwo-dimensional information sequence. In a complex and intensiveelectromagnetic environment, the TOA of pulses is distributedunevenly, randomly, and in a nonstationary manner, preventing existingmethods from directly analyzing such time series and effectivelyextracting certain signal features. This work applies Gaussiannoise insertion and structure function to the TOA-RF informationsequence respectively such that the equalization of time intervalsand correlation processing are accomplished. The componentswith different frequencies in structure function series are separatedusing empirical mode decomposition. Additionally, a chaos detectionmodel based on the Duffing equation is introduced to determinethe useful component and extract the changing features ofRF. Experimental results indicate that the proposed methodologycan successfully extract the slippage signal effectively in the casethat multiple radar pulse sequences overlap.

A New Control Strategy for a Three-Phase PWM Current-Source Rectifier in the Stationary Frame

Qiang Guo,Heping Liu,Yi Zhang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.4

This paper presents a novel power control strategy for PWM current-source rectifiers (CSRs) in the stationary frame based on the instantaneous power theory. In the proposed control strategy, a virtual resistance based on the capacitor voltage feedback is used to realize the active damping. In addition, the proportional resonant (PR) controller under the two-phase stationary coordinate is designed to track the ac reference current and to avoid the strong coupling brought about by the coordinate transformation. The limitations on improving steady-state performance of the PR controller is investigated and mitigated using a cascaded lead-lag compensator. In the z-domain, a straightforward procedure is developed to analyze and design the control-loop with the help of MATLAB/SISO software tools. In addition, robustness against parameter variations is analyzed. Finally, simulation and experimental results verify the proposed control scheme and design method.

Effect of harvest dates on β-carotene content and forage quality of rye (Secale cereale L.) silage and hay

( Guo Qiang Zhao ),( Sheng Nan Wei ),( Chang Liu ),( Hak Jin Kim ),( Jong Geun Kim ) 한국축산학회(구 한국동물자원과학회) 2021 한국축산학회지 Vol.63 No.2

Limited data about the effects of various factors on forage quality and β-carotene content of rye produced in Korea are available, so this study investigated the effects of two preservation methods. Samples were collected from rye harvested every 5 days between April 25 and May 31, and comparisons were done among rye silage wilted for different periods of time and hay of three growth stages of rye. For the silage, dry matter (DM), acid detergent fiber (ADF), and neutral detergent fiber (NDF) contents increased with advanced maturity of rye, whereas crude protein, in vitro dry matter digestibility (IVDMD), total digestible nutrients (TDN), relative feed value (RFV), and DM loss decreased (p < 0.0001). Wilting increased the DM content and pH value significantly (p < 0.0001). Silage harvested at the heading stage had the lowest pH value (4.45), propionic acid (0.83 g/kg DM), butyric acid (0 g/kg DM), and fungi and yeast populations (3.70 Log CFU/g of fresh matter [FM]); conversely, it had the highest lactic acid (9.7 g/kg DM), lactic acid bacteria (LAB) (6.87 Log CFU/g of FM), total microorganisms (TM) (7.33 Log CFU/g of FM), and Flieg’s score (70) (p < 0.0001). Wilting elevated LAB and TM populations, but it had no consistent effect on other fermentation products. Both delayed harvest and prolonged wilting decreased β-carotene content. Rye silage harvested around May 9 (heading stage) with 24 h of wilting was preferred for highland, Pyeongchang. For rye hay, advanced maturity decreased DM loss, IVDMD, TDN, and RFV, but it increased DM, ADF, and NDF significantly (p < 0.05). β-carotene was decreased by delay of hay-making. Consequently, to attain lower DM loss and higher hay quality, the harvest date of May 9 (heading stage) is recommended.

A QoS-Guaranteed Cell Selection Strategy for Heterogeneous Cellular Systems

Qiang Guo,Xianghua Xu,Jie Zhu,Haibin Zhang 한국전자통신연구원 2006 ETRI Journal Vol.28 No.1

In order to improve the accuracy of cell selection in heterogeneous cellular systems, this paper proposes a fuzzy multiple-objective decision-based cell selection (FMDCS) strategy. Since heterogeneous cellular systems have different access technologies and multiple traffic classes, the strategy adopts cell type, data rate, coverage, transmission delay, and call arrival rate as evaluation indices, and uses different weight vectors according to the traffic classes of the mobile host. Then, a fuzzy multipleobjective decision algorithm is applied to select the optimal cell from all candidates. This paper also gives an instance analysis and simulation. The instance analysis shows FMDCS makes different selections for different traffic classes. Simulation results of the after-handoff quality-ofservice (QoS) show the selected cell can provide MH optimal service.

A practical approach for fire safety design of fire-resistant steel members

Guo-Qiang Li,Jun Ding,Y. Sakumoto 국제구조공학회 2005 Steel and Composite Structures, An International J Vol.5 No.1

Based on the test data of Nippon Steel Corporation, the formulas for calculating mechanical properties of fire-resistant (FR) steel at elevated temperatures have been established. A practical approach for fire safety design of FR steel members, including axially compressed members, flexural members and eccentrically compressed members, is developed in this paper. Compared with the full-scale specimen experiments and FEM numerical analysis, this practical approach for fire safety design of FR steel members is demonstrated to be effective and precise.

Damage Localization of Steel Beams with Rotational Restraints

Guo-Qiang Li,Yang Zhang,Suwen Chen 한국강구조학회 2007 International Journal of Steel Structures Vol.7 No.1

In this paper, a method is presented for damage localization of stel beams with indexes based on natural frequencies becauselocations of beams and not related to the severity of damages is presented. Based on this principle, the universal curve-bankof the natural frequency indexes for damage localization of beams with rotational restraints is established. The effectivenessand universality of the curve-bank have been demonstrated by identifying the damage location of two steel beam specimenswith only first three natural frequencies of the beams. The approach presented may be used for monitoring the damagelocalization of beam-type structures, such as bridges.

Analysis of restrained heated steel beams during cooling phase

Guo-Qiang Li,Shi-Xiong Guo 국제구조공학회 2009 Steel and Composite Structures, An International J Vol.9 No.3

Observations from experiments and real fire indicate that restrained steel beams have better fireresistant capability than isolated beams. Due to the effects of restraints, a steel beam in fire condition can undergo very large deflections and the run away damage may be avoided. However disgusting damages may occur in the beam-to-column connections, which is considered to be mainly caused by the enormous axial tensile forces in steel beams resulted from temperature decreasing after fire dies out. Over the past ten years, the behaviour of restrained steel beams subjected to fire during heating has been experimentally and theoretically investigated in detail, and some simplified analytical approaches have been proposed. While the performance of restrained steel beams during cooling has not been so deeply studied. For the safety evaluation and repair of steel structures against fire, more detailed investigation on the behaviour of restrained steel beams subjected to fire during cooling is necessary. When the temperature decreases, the elastic modulus and yield strength of steel recover, and the contraction force in restrained steel beams will be produced. In this paper, an incremental method is proposed for analyzing the behaviour of restrained steel beams subjected to cooling. In each temperature decrement, the development of deformation and internal forces of a restrained beam is divided into four steps, in order to consider the effect of the recovery of the elastic modulus and strength of steel and the contraction force generated by temperature decrease in the beam respectively. At last, the proposed approach is validated by FE method.

Experimental Study on the Bend and Shear Behaviors of Steel-concrete Composite Beams with Notched Web of Inverted T-shaped Steel Section

Guo-Qiang Li,Xianhui Li,Liang Li 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.3

A new steel-concrete composite beam with notched web of inverted T-shaped steel section is proposed in this paper. This composite beam is composed of concrete slab and inverted T-shaped steel beam. Experimental studies on the bend and shear behavior of the composite beam are conducted. Four specimens are tested to investigate the bend behavior of the novel composite beam, and the formula for predicting the bend capacity is proposed and verified by comparing the results between predicted with the formula and the measured from the tests. Six specimens are also tested to study the shear behavior and the formula for estimating the shear capacity of the novel composite beam is recommended on the base of the test results. The formulas proposed in this paper may be employed to estimate the bend and shear capacity of the composite beam with notched web of inverted T-shaped steel section for application in practice.