Investigation of the Instability of FGM box beams

Ziane, Noureddine,Meftah, Sid Ahmed,Ruta, Giuseppe,Tounsi, Abdelouahed,Adda Bedia, El Abbas Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.3

A general geometrically non-linear model for lateral-torsional buckling of thick and thin-walled FGM box beams is presented. In this model primary and secondary torsional warping and shear effects are taken into account. The coupled equilibrium equations obtained from Galerkin's method are derived and the corresponding tangent matrix is used to compute the critical moments. General expression is derived for the lateral-torsional buckling load of unshearable FGM beams. The results are validated by comparison with a 3D finite element simulation using the code ABAQUS. The influences of the geometrical characteristics and the shear effects on the buckling loads are demonstrated through several case studies.

Line-to-line voltage based modulation scheme for single-phase reduced switch ac-dc-ac converters to achieve improved performance

Zian Qin,Poh Chiang Loh,Frede Blaabjerg 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Modulation methods can significantly influence the performance of the converter in steady state, which is therefore very important. With different objectives like the minimum current ripple, minimum power loss or maximum DC link voltage utilization, SVPWM or DPWM are normally applied. With the SVPWM or DPWM proposed in literatures, the generation of the references is phase voltage based. But the phase voltages actually cannot be controlled directly by the PWM converter, since they can be influenced by both of terminal voltages and the load network while the PWM converter can only control the former. It thus introduces complexity to the generation of the references, especially in unbalanced source or load condition. In this paper, a line-to-line voltage based PWM reference generation method is proposed. The proposed method is easy to be implemented to maximize the DC link voltage utilization, reduce current ripple, or improve the loss distribution. Analysis and experimental test are also given to verify the proposed method.

Er3+/Yb3+ Co-Doped Waveguide Amplifier and Lossless Power Splitter Fabricated by a Two-Step Ion Exchange on a Commercial Phosphate Glass

Zian He,Lei Xu,Dongxiao Li,Liying Liu,Yanwu Zhang,Yigang Li 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.5I

An Er3+/Yb3+ co-doped waveguide amplifier and a lossless power splitter were fabricated by two-step ion exchange on commercial Schott IOG-1 glasses. A two-dimensional ion exchange model was set up, and numerical simulations using a finite-element-method agreed well with experimental results. A total net gain of 6 dB was achieved in a 2.5-cm-long waveguide amplifier, and a lossless power splitter was successfully realized as well.kci

설명 가능한 정기예금 가입 여부 예측을 위한 앙상블 학습 기반 분류 모델들의 비교 분석

신지안(Zian Shin),문지훈(Jihoon Moon),노승민(Seungmin Rho) 한국전자거래학회 2021 한국전자거래학회지 Vol.26 No.3

정기예금 가입 여부 예측은 은행의 대표적인 금융 마케팅 중 하나로, 은행은 다양한 고객 정보를 활용하여 예측 모델을 구성할 수 있다. 정기예금 가입 여부의 분류 정확도를 향상하기 위해, 많은 연구에서 기계학습 기법들을 이용하여 분류 모델들을 개발하였다. 하지만, 이러한 모델들이 만족스러운 성능을 보일지라도 모델의 의사결정 과정에 대한 근거가 적절하게 설명되지 않는다면 산업에서 활용하기가 쉽지 않다. 이러한 문제점을 해결하기 위해, 본 논문은 설명 가능한 정기예금 가입 여부 예측 기법을 제안한다. 먼저, 테이블 형식에서 우수한 성능을 도출하는 의사결정 나무 기반 앙상블 학습 기법인 랜덤 포레스트, GBM, XGBoost, LightGBM을 이용하여 분류 모델들을 개발하고, 10겹 교차검증을 통해 모델들의 분류 성능을 심층 분석한다. 다음으로, 가장 우수한 성능을 도출하는 모델에 설명 가능한 인공지능 기법인 SHAP을 적용하여 고객 정보의 영향도와 의사결정 과정 등을 해석할 수 있는 근거를 제공한다. 제안한 기법의 실용성과 타당성을 입증하기 위해, Kaggle에서 제공한 은행 마케팅 데이터 셋을 대상으로 모의실험을 진행하였으며, 데이터 셋 구성에 따라 GBM과 LightGBM 모델에 SHAP을 각기 적용하여 설명 가능한 정기예금 가입 여부를 위한 분석 및 시각화를 수행하였다. Predicting term deposit subscriptions is one of representative financial marketing in banks, and banks can build a prediction model using various customer information. In order to improve the classification accuracy for term deposit subscriptions, many studies have been conducted based on machine learning techniques. However, even if these models can achieve satisfactory performance, utilizing them is not an easy task in the industry when their decision-making process is not adequately explained. To address this issue, this paper proposes an explainable scheme for term deposit subscription forecasting. For this, we first construct several classification models using decision tree-based ensemble learning methods, which yield excellent performance in tabular data, such as random forest, gradient boosting machine (GBM), extreme gradient boosting (XGB), and light gradient boosting machine (LightGBM). We then analyze their classification performance in depth through 10-fold cross-validation. After that, we provide the rationale for interpreting the influence of customer information and the decision-making process by applying Shapley additive explanation (SHAP), an explainable artificial intelligence technique, to the best classification model. To verify the practicality and validity of our scheme, experiments were conducted with the bank marketing dataset provided by Kaggle; we applied the SHAP to the GBM and LightGBM models, respectively, according to different dataset configurations and then performed their analysis and visualization for explainable term deposit subscriptions.

Investigation of the Instability of FGM box beams

Noureddine Ziane,Sid Ahmed Meftah,Giuseppe Ruta,Abdelouahed Tounsi,El Abbas Adda Bedia 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.3

A general geometrically non-linear model for lateral-torsional buckling of thick and thin-walled FGM box beams is presented. In this model primary and secondary torsional warping and shear effects are taken into account. The coupled equilibrium equations obtained from Galerkin's method are derived and the corresponding tangent matrix is used to compute the critical moments. General expression is derived for the lateral-torsional buckling load of unshearable FGM beams. The results are validated by comparison with a 3D finite element simulation using the code ABAQUS. The influences of the geometrical characteristics and the shear effects on the buckling loads are demonstrated through several case studies.

Recent development of high gradient superconducting magnetic separator for kaolin in china

Zhu Zian,Wang Meifen,Ning Feipeng,Yang Huan,Li Peiyong,Zhang Yiting,Wang Zhaolian,Zhang Guoqing,Hou Zhilong,Liu Zhongxiu,Dai Zhong 한국초전도저온학회 (구 한국초전도저온공학회) 2017 한국초전도저온공학회논문지 Vol.19 No.1

Exposed Reinforced Concrete-Filled Steel Tubular (RCFST) column-base joint with high-strength

Ben Mou,Zian Wang,Qiyun Qiao,Wanqiu Zhou 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.1

The weld quality has always been an important factor affecting the development of exposed CFT column-base joint. In this paper, a new type of exposed RCFST column-base joint is proposed, in which the high strength steel bars (USD 685) are set through the column and reinforced concrete foundation without any base plate and anchor bolts. Three specimens, the varying axial force ratio (0, 0.25 and 0.5), were tested under cyclic loadings. In addition, the bending moment capacity, energy dissipation capacity and deformation capacity of column-base joints were clarified. The experimental results indicated that the axial force ratio increases the stiffness and the bending moment and improves the energy dissipation capacity of column-base joints. This is because a large axial force can limit the slip between steel tubular and infilled concrete effectively. The specimens show stable hysteresis behavior.

A Digitally Controlled Three-Phase Cycloconverter Type High Frequency AC Link Inverter Using Space Vector Modulation

Deshang Sha,Zian Qin,Dan Wu,Xiaozhong Liao 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.1

In this paper, a three phase cycloconverter type high frequency AC link inverter is discussed. The configuration consists of a high frequency full-bridge inverter and a high frequency transformer followed by a three phase cycloconverter whose switch is composed of anti-series connected MOSFETs with a common source. A simple digital control strategy based on space vector modulation (SVM) and repetitive control for the cycloconverter is proposed although its input voltage is a high frequency AC pulse. The operation principle of the proposed control strategy is analyzed and the equivalent working modes during one interval are also presented. The effectiveness of the proposed control strategy is verified through Matlab/Simulink simulations and experiments on a 1.45㎾ prototype.

Improved Adaptive Compensation of Variant Fighter With Multiple Faults via Extended Observer

Kaiyu Hu,Wenjing Sun,Zian Cheng 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.7

This research is devoted to devising a fault-tolerant control system to resolve the challenge of multi-fault automatic repair in variable-structure flight conditions of fighters. In the classical fighter system, the increment of the state parameter is used to represent the variable structure parameter. To illustrate the broad applicability of the following technique, Rudder and Sensor Gain Loss and Bias Faults are constructed. The Extended Observer is designed to simultaneously gauge faults, states, and disturbances. Furthermore, the harmonic functions is designed to quickly adapt to fighter configuration changes, time-varying disturbances, and to estimate all failures. Similar harmonic functions also appear in the design of fault self-healing algorithms, i.e., adaptive fault-tolerant controllers with variable-structure harmonic functions, simultaneously repairing gain loss and bias faults of rudder and sensors. Verification of the method’s effectiveness is achieved through semi-physical simulations, while the Lyapunov function function demonstrates the system’s stability.

Fuzzy Adaptive Hybrid Compensation for Compound Faults of Hypersonic Flight Vehicle

Kaiyu Hu,Fuyang Chen,Zian Cheng 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.6

Based on the adaptive control technique, this study investigates the active-passive hybrid fault-tolerant control (FTC) for hypersonic flight vehicles (HFVs) with compound faults, including system and actuator faults. System and actuator compound faults are defined in multi-augmented Takagi-Sugeno fuzzy HFV systems. Indirect passive compensation factors shield the system faults. An observer with adaptive learning rates that combine fault magnitude and fuzzy premise variable is then designed to estimate actuator faults, where a novel bionic variable parameter algorithm improves the sensitivity and accuracy of fault estimation to the incipient fault deviations. Hence the fault-tolerant controller actively compensates for the actuator faults by using estimated information while shielding the system faults. Finally, the improved adaptive active-passive hybrid FTC for compound faults are completed, and the system’s robust stability is proven. Simulation results are provided to illustrate the effectivenessof the proposed FTC scheme.