800 publications from this institution
This paper proposes a novel hybrid‐driven digital twin (DT) framework for time‐variant reliability assessment of civil structures, which mainly consists of four modules, including physics model construction, data‐driven model calibration, failure probability calculation, and time‐variant reliability prediction. In the first module, a DT model of a specific structure is constructed to simulate structural dynamic responses. Then, an improved unscented Kalman filter (IUKF) algorithm is performed to continuously calibrate the parameters of DT model. Subsequently, in module 3, the subset simulation (SS) approach is employed to calculate failure probability of structures subjected to various model parameter samples, and the generated input–output samples are further applied for metamodel training. A Kriging metamodeling is used to construct the correlation between model parameters and structural failure probability. Once the metamodel is well trained, the time‐variant reliability assessment of structures can be continuously achieved in module 4. Numerical simulations on a Bouc–Wen model are conducted to validate the feasibility and accuracy of the proposed approach. Furthermore, a scaled column shake table structure is further employed to verify the effectiveness of the proposed approach. Both numerical and experimental results have shown that the proposed approach is capable of conducting time‐variant reliability assessment of civil structures.
对国内外钢箱梁桥面板设计要求进行对比分析,结合国内钢箱梁桥面设计研究成果及应用实例,对我国现行《公路钢箱梁桥面铺装设计与施工技术指南》中桥面板设计和施工技术要求进行探讨,供同行参考.
Abstract Based on the long-life test road of Yunluo expressway in Guangdong province, firstly, based on the theory of small disturbance elastic thin plate and the design code of the highway cement concrete pavement, the life analysis of the roller-compacted concrete pavement structure of the Yunluo long-life test road is carried out. The results show that the pavement structure can achieve a 53.2 years long-life. Secondly, in order to verify the reliability of the theoretical analysis results, the strain sensors and the temperature sensors were embedded in different layers of the test road. After years of continuous data collection and based on the constitutive model of the roller-compacted concrete material, the theoretical analysis of the results concluded that the pavement structure can achieve at least 45 years life. The results of theoretical and practical analysis show that the new type asphalt pavement structure on the roller-compacted concrete base can be used as a typical long-life asphalt pavement structure under high temperature, rainy and heavy load conditions in Guangdong province.
loss of structural dynamic response measurements at the carefully selected locations of structural health monitoring (shm) systems can happen because of the uncontrollable in-field measurement condition. Investigation of reconstructing the lost response is an urgent need for shm. This paper proposes a response reconstruction method based on a specially designed deep learning model, that is a fully convolutional neural network. It features skip connections and densely connected blocks for improving information flow. The network is trained by a supervised manner with input and output defined as responses of available and desired locations. The effectiveness and robustness of the developed approach are validated by using measured acceleration data from guangzhou new tv tower. The proposed method exhibits a strong capability on structural response reconstruction, which effectively predicts the useful information of unavailable responses and eliminates measurement noise.
1. IntroductionThis research was conducted to evaluate the effectiveness of various aspects of a ten-year multi-million dollar executive leadership program, which was designed and delivered in Australia for Chinese oil and gas sector middle and senior managers over a ten-year period. Initially the program had run annually for six months, but after six years it ran twice a year for shorter three-month courses. The program was a non-award but MBA level program that explored aspects of leadership, management and economics within the Chinese oil and gas sector. The participants on the program along with alumni were invited to participate in the research. These participants were asked to comment on four key areas of interest to the researchers including: their opinion of the effectiveness of the program; aspects of social capital support; industry-based human capital; and, their opinions about Chinese energy policy.During the ten years of the program the Program Managers had provided formative and summative reports on each of the six- or three-month courses. This information along with anecdotal information from the Program Director, also a research team member, provided an excellent starting point for the survey.The focus of the research, which we want to explore and present here, is related to lessons learnt from undertaking a culturally sensitive mixed methods study with a multidisciplinary team of researchers. First, we present the multidisciplinary team and a review of cultural sensitive research techniques and the issues that arise when undertaking this. The actual mixed methods research design developed and employed is then presented followed by the actual approach and methodological choices we made.2. Multidisciplinary research teamOur research team consisted of three people: two women, one man. Two of our members are research fellows of the same university; the third member started as an academic of the same university and is now an adjunct staff member. One team member was the Director of the executive education program being studied and thus had access to the contact details, program staff and could readily seek the Board's permission, as well as university ethics permission, for the research. She was also known to the participants, which, in this case, assisted to minimise any perceived intimidation of respondents. One team member is Chinese with strong connections across both Australia and China. One researcher is a mixed method expert and researcher. One researcher is an expert and researcher in facilitation of focus groups. Table 1 summarises the spread of relevant researcher expertise and qualities relating to this paper.The research team decided to use a mixed methods approach where quantitative data would be collected from the current cohort and all previous cohorts who had returned to China. This would then be followed by a focus group with the current cohort who was, at the time, in Australia undertaking the leadership program. This qualitative data would provide the team with a much richer set of data to compliment the quantitative data. The research team acknowledged the knowledge base and research skill sets of each team member and made explicit decisions to leverage off these knowledge and skills when undertaking the study.3. Culturally sensitive research techniquesIn our research we were conscious of the methods we might use to gather data from many aspects including cultural sensitivity. We were three Australian-based researchers wanting information from Chinese participants. Some of those participants were located in Australia; some had met one or more of the researchers through the executive education program; some had returned to China many years before and had, possibly, only a distance memory of the program, did not know any of the researchers and had not communicated in English for some time. It was with these elements in mind that we tried to ensure our data gathering strategies were culturally sensitive. …
Abstract Failure rate is very important for the reliability and risk assessment of in-service pressure vessels. As early as in the 1970s and 1980s, the failure rate data of in-service pressure vessels has been collected in various countries, such as Europe and the United States, and in great detail. These data were incorporated into the relevant reliability database such as OREDA and CEMHD5. However, the failure rate data of pressure vessels in China is rarely reported so far, which limits the development of reliability and risk assessment technology for the pressure vessels in non-nuclear and nuclear industries. In this paper, about fifty thousand in-service pressure vessels data in China’s non-nuclear industry were collected. The potential and catastrophic failure rate were counted based on exponential distribution model. The statistical results were compared and analyzed with those of other countries such as the United States, the United Kingdom and Germany. The analysis results showed that the thickness thinning and cracking caused by corrosive medium were two main causes for pressure vessel failures in China. The failure rate of in-service pressure vessels in China is higher than that in the Europe and the United States countries, which may be caused by the high sulfur and high acid crude oil.
An approach for structural response reconstruction in a substructure using the unit impulse response function in the wavelet domain is presented. The forces at the interface degrees-of-freedom are taken as input excitations on the substructure. The response reconstruction is conducted by transforming the measured responses into responses at other selected locations. The response reconstruction using the proposed wavelet domain method is then compared with that from an existing frequency domain method. Numerical studies on a seven-story plane frame structure are carried out to investigate the accuracy and effectiveness of the proposed method, and the effects of influencing parameters such as the number of sampled data, sampling rate, sensor numbers, and measurement noise are studied.
Remote monitoring of distributed mariculture based on Internet of Things (IoT) has become an important part of smart marine agriculture, however, attaining stable and long-lasting power supply from conventional commercial batteries remains challenging, which significantly restricts the development of blue economic toward intelligent and diversified. Herein, a self-powered monitoring and warning system (SMWS) for smart mariculture based on a nodding duck structured multi-layer hybrid triboelectric-electromagnetic generator (MHTEG) is developed that endows improved electrical output performances and energy conversion efficiency. Through optimizing the configuration parameters, a maximum instantaneous output power density of 20.9 W/m3, ultra-high output energy of 39.6 mJ and excellent energy conversion efficiency of 22.61% can be achieved by the MHTEG with a high charge transfer efficiency of over 88%. Moreover, combining the MHTEG with an anti-theft and seawater sensor module, the remote SMWS is designed for monitoring and providing early-warning in marine farming. Such a design renders a practicable strategy and generic energy solution for efficient ocean wave energy scavenging and enabling distributed mariculture with intelligence.
In order to enhance the application value of the transportation data center further, it was essential to use business intelligence (BI) technology for data mining, analyzing, and displaying. On the basis of summarizing the status and trend of BI technology for data display and analysis, the general methods of the analysis process for the data center were summarized. Taking the taxi meter data of Beijing as an example, the structure of the original data was analyzed and the calculation method for the taxi operation index was put forward. The indexes were put forward, including operation mileage, operation time, number of carrying passengers, income, and so on. They were analyzed from different dimensions using BI technology. The functions of historical data query, report output, and others were provided, supporting the taxi operation management and decision.
In this paper, a new method is proposed for designing stable controllers with arbitrarily small tracking error for nonlinear systems with unmatched uncertainties. The proposed approach is based upon a combination of the backstepping design method and the variable structure control scheme to design backstepping VS controller and provide robust output tracking even in the presence of unknown disturbance. The closed loop systems reach the sliding surface in a finite time. Simulations are provided to illustrate the performance of the controller.
Abstract Primary frequency control(PFC) of thermal power unit is an important means to ensure power supply frequency and safe and stable operation of power grid. Through the analysis and research of the PFC standard of the power grid, combined with the control structure of conventional thermal power units, it is pointed out that the delay and inertia inherent in the unit equipment have a negative impact on the PFC performance. From two directions of field dynamic test and laboratory simulation, existing problems of currently widely used control structures are clearly defined, and the technical means of reducing the influence of delay on PFC are proposed. The practical application results show that the proposed method can effectively reduce the overshoot of the PFC system and ensure that the system recovers quickly and stably.
