Probabilistic-based prediction of lifetime performance of RC bridges subject to maintenance interventions

Hao Tian,Fangyuan Li 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.4

In this paper, a probabilistic- and finite element-based approach to evaluate and predict the lifetime performance of reinforced concrete (RC) bridges undergoing various maintenance actions is proposed with the time-variant system reliability being utilized as a performance indicator. Depending on their structural state during the degradation process, the classical maintenance actions for RC bridges are firstly categorized into four types: Preventive type I, Preventive type II, Strengthening and Replacement. Preventive type I is used to delay the onset of steel corrosion, Preventive type II can suppress the corrosion process of reinforcing steel, Strengthening is the application of various maintenance materials to improve the structural performance and Replacement is performed to restore the individual components or overall structure to their original conditions. The quantitative influence of these maintenance types on structural performance is investigated and the respective analysis modules are written and inputted into the computer program. Accordingly, the time-variant system reliability can be calculated by the use of Monte Carlo simulations and the updated the program. Finally, an existing RC continuous bridge located in Shanghai, China, is used as an illustrative example and the lifetime structural performance with and without each of the maintenance types are discussed. It is felt that the proposed approach can be applied to various RC bridges with different structural configurations, construction methods and environmental conditions.

Study on the Microstructure of Single Stage Hot Deformed Anisotropic Nd-Fe-B Magnets

Hao Tian,Ying Li,Mingyuan Zhu,Hongming Jin,Dongzhe Jin 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Computational Investigation on Unsteady Loads of High-Speed Rigid Coaxial Rotor with High-Efficient Trim Model

Haotian Qi,Guo-hua Xu,Congling Lu,Yong-jie Shi 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.1

A computational fluid dynamics method is built to study the unsteady aerodynamic loads of a high-speed rigid coaxial rotor model, taking account of lift offset (LOS). The flowfield is simulated by solving Reynolds Averaged Navier–Stokes equations, and moving overset mesh is adopted to include blade motions. A high-efficient trim model for coaxial rotor is developed, where the “delta method” is implemented. Performance of Harrington rotor-1 is calculated for validation. Forward flight cases in three advance ratios are conducted. Results indicate that the temporal thrusts of coaxial rotor at low advance ratio share some fluctuations similar to hover state. In forward flight, the impulsive thrust fluctuations caused by blade-meeting are obviously exhibited around 270° for upper blades, and the strengths increase with the increase of LOS and advance ratio. At higher advance ratios, the blade thrusts of the upper and lower rotors tend to be the same. At the advance ratio of 0.6, two new kinds of Blade–vortex interaction (BVI) are captured. One is the parallel BVI caused by the root vortex and the other is the complex interaction among the tip vortex, root vortex and the rear blade.

Nonlocal bending, vibration and buckling of one-dimensional hexagonal quasicrystal layered nanoplates with imperfect interfaces

Haotian Wang,Junhong Guo 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.6

Due to interfacial ageing, chemical action and interfacial damage, the interface debonding may appear in the interfaces of composite laminates. Particularly, the laminates display a side-dependent effect at small scale. In this work, a threedimensional (3D) and anisotropic thick nanoplate model is proposed to investigate the effects of imperfect interface and nonlocal parameter on the bending deformation, vibrational response and buckling stability of one-dimensional (1D) hexagonal quasicrystal (QC) layered nanoplates. By combining the linear spring model with the transferring matrix method, exact solutions of phonon and phason displacements, phonon and phason stresses of bending deformation, the natural frequencies of vibration and the critical buckling loads of 1D hexagonal QC layered nanoplates are derived with imperfect interfaces and nonlocal effects. Numerical examples are illustrated to demonstrate the effects of the imperfect interface parameter, aspect ratio, thickness, nonlocal parameter, and stacking sequence on the bending deformation, the vibrational response and the critical buckling load of 1D hexagonal QC layered nanoplate. The results indicate that both the interface debonding and nonlocal effect can reduce the stiffness and stability of layered nanoplates. Increasing thickness of QC coatings can enhance the stability of sandwich nanoplates with the perfect interfaces, while it can reduce first and then enhance the stability of sandwich nanoplates with the imperfect interfaces. The biaxial compression easily results in an instability of the QC layered nanoplates compared to uniaxial compression. QC material is suitable for surface layers in layered structures. The mechanical behavior of QC layered nanoplates can be optimized by imposing imperfect interfaces and controlling the stacking sequence artificially. The present solutions are helpful for the various numerical methods, thin nanoplate theories and the optimal design of QC nano-composites in engineering practice with interfacial debonding.

Trigger design for timer-actuated point-of-care testing device

Haotian Ma(마호전),Sung-Jin Kim(김성진) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.5

Constrained Variational Policy Optimization for Emergency Load Shedding of Power Systems

Haotian Zhang,Xinfeng Sun,Myoung Hoon Lee,Jun Moon 제어로봇시스템학회 2023 제어로봇시스템학회 국내학술대회 논문집 Vol.2023 No.6

Task offloading under deterministic demand for vehicular edge computing

Haotian Li,Xujie Li,Fei Shen Electronics and Telecommunications Research Instit 2023 ETRI Journal Vol.45 No.4

In vehicular edge computing (VEC) networks, the rapid expansion of intelligent transportation and the corresponding enormous numbers of tasks bring stringent requirements on timely task offloading. However, many tasks typically appear within a short period rather than arriving simultaneously, which makes it difficult to realize effective and efficient resource scheduling. In addition, some key information about tasks could be learned due to the regular data collection and uploading processes of sensors, which may contribute to developing effective offloading strategies. Thus, in this paper, we propose a model that considers the deterministic demand of multiple tasks. It is possible to generate effective resource reservations or early preparation decisions in offloading strategies if some feature information of the deterministic demand can be obtained in advance. We formulate our scenario as a 0-1 programming problem to minimize the average delay of tasks and transform it into a convex form. Finally, we proposed an efficient optimal offloading algorithm that uses the interior point method. Simulation results demonstrate that the proposed algorithm has great advantages in optimizing offloading utility.

Study on seismic performance of connection joint between prefabricated prestressed concrete beams and high strength reinforcement-confined concrete columns

Haotian Jiang,Qingning Li,Weishan Jiang,De-Yi Zhang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.2

As the common cast-in-place construction works fails to meet the enormous construction demand under rapid economic growth, the development of prefabricated structure instead becomes increasingly promising in China. For the prefabricated structure, its load carrying connection joint play a key role in maintaining the structural integrity. Therefore, a novel end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and highstrength reinforcement-confined concrete column was proposed. Under action of low cycle repeated horizontal loadings, comparative tests are conducted on 6 prefabricated pre-stressed intermediate joint specimens and 1 cast-inplace joint specimen to obtain the specimen failure modes, hysteresis curves, skeleton curves, ductility factor, stiffness degradation and energy dissipation capacity and other seismic indicators, and the seismic characteristics of the new-type prefabricated beam-column connecting joint are determined. The test results show that all the specimens for end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and highstrength reinforcement-confined concrete column have realized the design objectives of strong column weak beam. The hysteretic curves for specimens are good, indicating desirable ductility and energy dissipation capacity and seismic performances, and the research results provide theoretical basis and technical support for the promotion and application of prefabricated assembly frames in the earthquake zone.

LSTM-based Model for Effective Sensor Filtering in Sensor Registry System

Haotian Chen(천하오티엔),Hyunjun Jung(정현준),Sukhoon Lee(이석훈),Byung-Won On(온병원),Dongwon Jeong(정동원) 한국정보통신학회 2021 한국정보통신학회 종합학술대회 논문집 Vol.25 No.2

센서 레지스트리 시스템은 센서와 디바이스 간 상호운용성 문제를 해결하기 위하여 모바일 디바이스의 위치 정보에 기반하여 센서에 대한 의미적 메타데이터를 제공한다. 하지만 모바일 디바이스의 GPS가 잘못 수신되면 센서 레지스트리 시스템은 잘못된 센서 정보를 받게 되며 센서와 연결할 수 없다는 문제를 지닌다. 이 논문에서는 이러한 문제를 해결하기 위해 모바일 장치와 센서 간의 성공적인 요청 확률을 향상시키기 위해 지리적 임베딩 및 LSTM 기반 경로 예측을 기반으로 한 이중 협업 전략을 제안하고 몬테카를로 방법을 이용하여 평가한다. 실험을 통하여, 제안한 방법이 위치 이상 문제를 개선하고 효과적인 멀티캐스팅 메카니즘임을 보였다. A sensor registry system (SRS) provides semantic metadata about a sensor based on location information of a mobile device in order to solve a problem of interoperability between a sensor and a device. However, if the GPS of the mobile device is incorrectly received, the SRS receives incorrect sensor information and has a problem in that it cannot connect with the sensor. This paper proposes a dual collaboration strategy based on geographical embedding and LSTM-based path prediction to improve the probability of successful requests between mobile devices and sensors to address this problem and evaluate with the Monte Carlo approach. Through experiments, it was shown that the proposed method can compensate for location abnormalities and is an effective multicasting mechanism.

Partial Observer Canonical Form Design Method for Single-output Affine Nonlinear System with Simple Validation Conditions

Haotian Xu,Jingcheng Wang 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.7

The problem concerning observer error linearization is to find a new state coordinate transformation (diffeomorphism) to transform the underlying nonlinear system into a Partial Observer Canonical Form (POCF). Since the complexity of the existing verification conditions associated with the existence of POCF, this paper develops a two-steps method for calculating POCF to simplify the verification conditions. This method also shows that POCF is equivalent to a compound diffeomorphism that consists of two coordinate transformations. One of them is a diffeomorphism which transforms the system into an observable canonical form based on maximum invariant distribution, and the other one is a diffeomorphism of transforming the observable subsystem into an observer linearization form. With the help of this method, a part of the original conditions are replaced by a group of new conditions that are easier to be verified, and another part of the original conditions are proved to be redundant and could not be verified anymore. At last, three examples are used to demonstrate the validity of this paper.