Mechanical Property Evaluation of TSV-Cu Micropillar by Compression Method

Ting Gu,Ping Cheng,Su Wang,Huiying Wang,Xuhan Dai,Hong Wang,Guifu Ding 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.4

A micro-compression test method was presented to evaluate the mechanical property of the TSV-Cu micropillar in this paper. Firstly, the test sample containing TSV-Cu micropillar was prepared by MEMS micromachining technology. Then, the mechanical property of TSV-Cu micropillar was measured by a self-made micro-compression system. Finally, the effect of thermal treatment on the mechanical property of TSV-Cu micropillar was studied. The experimental results showed that the average yield strength (σ0.2) of the TSV-Cu micropillar was 167 MPa. But it decreased to 137 MPa after being thermally treated at 400°C for 1 hour, which was probably due to the increased grain size of Cu.

近代东南亚华族移民重商原因之探讨

古鴻廷(Gu, Hong-Ting),曹淑?(Cao, Shu-Yao) 전남대학교 글로벌디아스포라연구소 2008 디아스포라 연구 Vol.2 No.1

Wavelet based multi-step filtering method for bridge health monitoring using GPS and accelerometer

Ting-Hua Yi,Hong-Nan Li,Ming Gu 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.11 No.4

Effective monitoring, reliable data analysis, and rational data interpretations are challenges for engineers who are specialized in bridge health monitoring. This paper demonstrates how to use the Global Positioning System (GPS) and accelerometer data to accurately extract static and quasi-static displacements of the bridge induced by ambient effects. To eliminate the disadvantages of the two separate units, based on the characteristics of the bias terms derived from the GPS and accelerometer respectively, a wavelet based multi-step filtering method by combining the merits of the continuous wavelet transform (CWT) with the discrete stationary wavelet transform (SWT) is proposed so as to address the GPS deformation monitoring application more efficiently. The field measurements are carried out on an existing suspension bridge under the normal operation without any traffic interference. Experimental results showed that the frequencies and absolute displacements of the bridge can be accurate extracted by the proposed method. The integration of GPS and accelerometer can be used as a reliable tool to characterize the dynamic behavior of large structures such as suspension bridges undergoing environmental loads.

An Evolving-Graph-Based Finite State Machine Model for Protocol Conformance Testing in MANETs

Ting Shu,Mangmang Gu,Jinsong Xia 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.10

Dynamic network topology is one of the inherent features of Mobile Ad hoc Network (MANET). However, it may lead to unfeasible test sequences in the FSM-based active conformance testing, due to the topological distinction between testing sequences generation and its execution. In this paper, a formal model, named Evolving-Graph- based Finite State Machine (EGFSM), is proposed to help alleviate the impact of the dynamic network on conformance testing in MANETs. The evolving graph theory is first introduced to extend the Finite State Machine model to describe the dynamic behavior of the protocol with time-varying network topology. In the testing scenario with a predictable node movement pattern, test sequences adaptable to the dynamic topological changescan be generated on the basis of the EGFSM for the protocol under testing. A case study based on the AODV routing protocol is conducted, and promising experimental results show that it is a feasible way to test the protocols in MANETs using an EGFSM.

A new method for optimal selection of sensor location on a high-rise building using simplified finite element model

Ting-Hua Yi,Hong-Nan Li,Ming Gu 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.6

Deciding on an optimal sensor placement (OSP) is a common problem encountered in many engineering applications and is also a critical issue in the construction and implementation of an effective structural health monitoring (SHM) system. The present study focuses with techniques for selecting optimal sensor locations in a sensor network designed to monitor the health condition of Dalian World Trade Building which is the tallest in the northeast of China. Since the number of degree-of-freedom (DOF) of the building structure is too large, multi-modes should be selected to describe the dynamic behavior of a structural system with sufficient accuracy to allow its health state to be determined effectively. However, it’s difficult to accurately distinguish the translational and rotational modes for the flexible structures with closely spaced modes by the modal participation mass ratios. In this paper, a new method of the OSP that computing the mode shape matrix in the weak axis of structure by the simplified multi-DOF system was presented based on the equivalent rigidity parameter identification method. The initial sensor assignment was obtained by the QR-factorization of the structural mode shape matrix. Taking the maximum off-diagonal element of the modal assurance criterion (MAC) matrix as a target function, one more sensor was added each time until the maximum off-diagonal element of the MAC reaches the threshold. Considering the economic factors, the final plan of sensor placement was determined. The numerical example demonstrated the feasibility and effectiveness of the proposed scheme.

Cable anomaly detection driven by spatiotemporal correlation dissimilarity measurements of bridge grouped cable forces

Ting-Hua Yi,Dong-Hui Yang,Hai-Lun Gu,Zhanjun Wu 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.6

Stayed cables are the key components for transmitting loads in cable-stayed bridges. Therefore, it is very important to evaluate the cable force condition to ensure bridge safety. An online condition assessment and anomaly localization method is proposed for cables based on the spatiotemporal correlation of grouped cable forces. First, an anomaly sensitive feature index is obtained based on the distribution characteristics of grouped cable forces. Second, an adaptive anomaly detection method based on the <i>k</i>-nearest neighbor rule is used to perform dissimilarity measurements on the extracted feature index, and such a method can effectively remove the interference of environment factors and vehicle loads on online condition assessment of the grouped cable forces. Furthermore, an online anomaly isolation and localization method for stay cables is established, and the complete decomposition contributions method is used to decompose the feature matrix of the grouped cable forces and build an anomaly isolation index. Finally, case studies were carried out to validate the proposed method using an in-service cable-stayed bridge equipped with a structural health monitoring system. The results show that the proposed approach is sensitive to the abnormal distribution of grouped cable forces and is robust to the influence of interference factors. In addition, the proposed approach can also localize the cables with abnormal cable forces online, which can be successfully applied to the field monitoring of cables for cable-stayed bridges.

Sensor placement for structural health monitoring of Canton Tower

Ting-Hua Yi,Hong-Nan Li,Ming Gu 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.10 No.4

A challenging issue in design and implementation of an effective structural health monitoring (SHM) system is to determine where a number of sensors are properly installed. In this paper, research on the optimal sensor placement (OSP) is carried out on the Canton Tower (formerly named Guangzhou New Television Tower) of 610 m high. To avoid the intensive computationally-demanding problem caused by tens of thousands of degrees of freedom (DOFs) involved in the dynamic analysis, the three dimension finite element (FE) model of the Canton Tower is first simplified to a system with less DOFs. Considering that the sensors can be physically arranged only in the translational DOFs of the structure, but not in the rotational DOFs, a new method of taking the horizontal DOF as the master DOF and rotational DOF as the slave DOF, and reducing the slave DOF by model reduction is proposed. The reduced model is obtained by IIRS method and compared with the models reduced by Guyan, Kuhar, and IRS methods. Finally, the OSP of the Canton Tower is obtained by a kind of dual-structure coding based generalized genetic algorithm (GGA).

The Disadvantageous Influence and Improvement Measures of Stator Slot Skewed Structures on the Damper Winding Loss and Stator Core Loss of Tubular Hydro-Generators

Gu Shi-fu,Bian Zu-ying,Zhou Zhi-ting,Yang Yong,Fan Zhen-nan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4

In this paper, a 34-MW integer slot tubular hydro- generator and an 18-MW fractional slot tubular hydro-generator were selected as examples to study the influence of the stator slot skewed structure on the damper winding loss, the stator core loss, and the no-load voltage waveform. The conclusions showed that although the stator slot skewed structure undoubtedly helped in improving the quality of the generator's no-load voltage waveform, it led to a significant increase in the eddy current loss of the damper winding and to an uneven distribution of the damper winding loss and stator core loss, which means that along the axis direction of the generator, the density of the damper winding loss and stator core loss significantly increased with the increase in the stator slot skewed degree. On this basis, the necessary measures for overcoming the above-mentioned disadvantages were discussed. Overall, the conducted research in this paper has direct and important reference values for improving the design and manufacturing levels of tubular hydro-generators, reducing their losses and heat, and optimizing their power quality.

Sensor placement for structural health monitoring of Canton Tower

Yi, Ting-Hua,Li, Hong-Nan,Gu, Ming Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.10 No.4

A challenging issue in design and implementation of an effective structural health monitoring (SHM) system is to determine where a number of sensors are properly installed. In this paper, research on the optimal sensor placement (OSP) is carried out on the Canton Tower (formerly named Guangzhou New Television Tower) of 610 m high. To avoid the intensive computationally-demanding problem caused by tens of thousands of degrees of freedom (DOFs) involved in the dynamic analysis, the three dimension finite element (FE) model of the Canton Tower is first simplified to a system with less DOFs. Considering that the sensors can be physically arranged only in the translational DOFs of the structure, but not in the rotational DOFs, a new method of taking the horizontal DOF as the master DOF and rotational DOF as the slave DOF, and reducing the slave DOF by model reduction is proposed. The reduced model is obtained by IIRS method and compared with the models reduced by Guyan, Kuhar, and IRS methods. Finally, the OSP of the Canton Tower is obtained by a kind of dual-structure coding based generalized genetic algorithm (GGA).

A new method for optimal selection of sensor location on a high-rise building using simplified finite element model

Yi, Ting-Hua,Li, Hong-Nan,Gu, Ming Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.6

Deciding on an optimal sensor placement (OSP) is a common problem encountered in many engineering applications and is also a critical issue in the construction and implementation of an effective structural health monitoring (SHM) system. The present study focuses with techniques for selecting optimal sensor locations in a sensor network designed to monitor the health condition of Dalian World Trade Building which is the tallest in the northeast of China. Since the number of degree-of-freedom (DOF) of the building structure is too large, multi-modes should be selected to describe the dynamic behavior of a structural system with sufficient accuracy to allow its health state to be determined effectively. However, it's difficult to accurately distinguish the translational and rotational modes for the flexible structures with closely spaced modes by the modal participation mass ratios. In this paper, a new method of the OSP that computing the mode shape matrix in the weak axis of structure by the simplified multi-DOF system was presented based on the equivalent rigidity parameter identification method. The initial sensor assignment was obtained by the QR-factorization of the structural mode shape matrix. Taking the maximum off-diagonal element of the modal assurance criterion (MAC) matrix as a target function, one more sensor was added each time until the maximum off-diagonal element of the MAC reaches the threshold. Considering the economic factors, the final plan of sensor placement was determined. The numerical example demonstrated the feasibility and effectiveness of the proposed scheme.