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百年期刊
ISSN 1000-0585
CN 11-1848/P
Started in 1982
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Table of Content
, Volume 62 Issue 2
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SPECIAL SECTION:CONSTRUCTION MANAGEMENT
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Automatic generation of construction schedules based on BIM and rule reasoning
GUO Hongling, YE Xiaotian, REN Qipeng, LUO Zhubang
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 189-198. DOI: 10.16511/j.cnki.qhdxxb.2022.22.001
Abstract
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Construction schedules are key to effective construction management and construction process simulations. Automatically generated schedules can improve scheduling accuracy and efficiency. However, most relevant research has focused on case-based or model-based approaches which cannot accurately match the conditions in other projects and only consider spatial constraints without detailed knowledge rules. This research focuses on the most common hybrid concrete structures. This article describes the coding system and the decomposition of the construction activities suitable for automatic scheduling. The constraint rules between various components or construction activities are then analyzed to infer the logical sequences between them. The building quantities extracted from the building information modeling (BIM) based on the industry foundation classes (IFC) are used to calculate the duration of each construction activity to automatically generate component-level schedules. This then provides the time sequence for construction simulation and automation for intelligent construction equipment.
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BIM-based, data-driven method for intelligent operation and maintenance
HU Zhenzhong, LENG Shuo, YUAN Shuang
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 199-207. DOI: 10.16511/j.cnki.qhdxxb.2022.22.003
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Building information models (BIM) provide improved building operation and maintenance (O&M) efficiencies. However, BIM-based intelligent O&M still faces challenges related to data acquisition, integration and analysis. This paper combines BIM and data-driven techniques to develop a solution for intelligent O&M. This approach includes a method to identify upstream and downstream relationships among mechanical, electrical and plumbing (MEP) facilities to supplement the O&M information in BIM. A data cube model is then used to integrate the BIM and building information. Multiple data mining methods including clustering, frequent pattern discovery and neural networks are then used to analyze the O&M data and assist intelligent decision-making. This method reduces the O&M personnel workload, increases the O&M data value, and improves the intelligence level of the O&M management.
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Mining safety hazard management collaboration features from large construction projects
ZHANG Dongcheng, QIANG Maoshan, JIANG Hanchen, HUANG Yujie
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 208-214. DOI: 10.16511/j.cnki.qhdxxb.2021.22.045
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Safety hazard management of large construction projects is essential to ensuring construction safety. This study used text mining of safety hazard management information for more than three years collected from a large construction project's information system with automatic word segmentation, part-of-speech tagging and term frequency (TF)-inverse document frequency (IDF) analyses to extract and classify hazard features. This methodology analyzes the safety hazard features to identify the safety hazard conditions on site in real time. The hazard features are further analyzed by different hazard types and different roles of the organizations. This study also investigates the impact of the hazard features on the management efficiency. This paper provides an effective on site safety hazard management method which can help managers focus on the key needs and improve construction efficiency.
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Critical construction scenarios, elements and development paths for intelligent construction platforms
ZHANG Hao, MA Ling, TIAN Shichuan, GUO Hongling
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 215-220. DOI: 10.16511/j.cnki.qhdxxb.2022.22.004
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Intelligent construction methods are being rapidly developed with various intelligent construction products being developed, such as intelligent construction platforms. However, these intelligent construction methods are still in their early development stage. Few previous studies have considered critical construction scenarios, elements and future development paths of intelligent construction platforms. This study analyzes typical foreign and domestic construction platform cases to identify the critical construction scenarios and elements of effective construction platforms through a literature review and expert interviews. Future developments in the fields of intelligent construction platforms will go through 5 stages (mechanisation, semi-automation of a certain process, semi-automation of multiple processes, full automation of multiple processes, and full automation) with different critical construction scenarios, degrees of automation, safety supervision and platform system benefits. This study will provide references for rapid development of intelligent construction platforms.
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Safety leadership characteristics and key dimensions of building industry regulators
MA Linyao, WANG Yao, HUANG Yuecheng, LI Pengcheng, FANG Dongping
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 221-229. DOI: 10.16511/j.cnki.qhdxxb.2021.22.043
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The importance of safety leadership in the construction industry has been widely recognized. However, previous studies have largely focused on the internal stakeholders in construction projects with no systematic discussion of the importance of safety leadership among the building industry regulators who are important external stakeholders. This study looks at the regulatory, supervisory and service functions of the building industry regulators to analyze the safety leadership characteristics of building industry regulators in terms of their organizational safety goals, leader-member interactions and leadership style. Then, a thematic analysis is used to identify four key dimensions of the building industry regulator safety leadership including leading by example and providing vision and inspiration, concern and respect, performance control, and their indicators. Finally, the results show that Chinese building industry regulators most commonly provide strong control and weak guidance. These findings can help building industry regulators to clearly understand, evaluate and improve their own safety leadership to improve construction industry safety.
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Analysis of factors influencing HSE management and project performance in international construction projects
SUN Hongxin, YOU Richun, TANG Wenzhe
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 230-241. DOI: 10.16511/j.cnki.qhdxxb.2022.22.002
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Complex internal and external environmental factors impact international construction project management. A model was developed for Chinese international contractors to analyze the factors influencing the health, safety and environment (HSE) management and project performance which was then verified with empirical evidence from questionnaire surveys. The main conclusions are:Both internal and external environmental factors positively influence HSE management; external environmental factors both directly and indirectly affect project performance; and internal environment factors can indirectly influence project performance through the mediating effect of HSE management. This study also shows the latent relationships between the external environment, internal environment, HSE management and project performance. Management strategies are then given to provide practical guidance for market expansion and project delivery for Chinese international contractors.
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Risk management of international EPCprojects through partnering
WANG Tengfei, WANG Yunhong, SHEN Wenxin, TANG Wenzhe
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 242-249. DOI: 10.16511/j.cnki.qhdxxb.2022.22.008
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The Belt and Road Initiative has lead to many Chinese enterprises actively participating in the international engineering- procurement-construction (EPC) market. Risk management is essential for EPC project delivery. However, existing research has mostly used only conceptual studies to explore the use of partnering strategies in risk management without mechanism analyses and validation using empirical data. This paper presents a risk management model based on partnering theory that is evaluated using questionnaire data and the partial least squares structural equation modeling (PLS-SEM) method. The results show the relationships among partnering, risk management and project performance and verify that partnerships between the contractor and various stakeholders improve interface management, organizational capacity and contract management to achieve effective risk management and continuous improvement of project performance. The results highlight the importance of partnering and risk management for EPC project performance and contribute to improving risk management of Chinese EPC contractors.
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Case studies of the return structure of urban underground comprehensive pipeline gallery PPP projects
ZHAO Guofu, WANG Shouqing
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 250-258. DOI: 10.16511/j.cnki.qhdxxb.2022.22.005
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Public-private partnerships (PPP) play important roles in constructing and operating domestic urban underground comprehensive pipeline galleries. However, the return mechanism and the return structure are not well understood with little research on the key factors and the application of quantitative analysis tools. This article presents case studies of the return mechanisms and return structures of 71 domestic urban underground pipeline gallery PPP projects that are already operating. A stakeholder analysis shows the livelihood attributes of the pipeline gallery and enterprise interests. The return mechanisms and return structures are then analyzed using the principle of "substance over form" to analyze the key factors. Finally, a return structure model is presented for urban underground comprehensive pipeline gallery PPP projects based on the discounted cash flow and net present value (NPV)-internal rate of return (IRR) which can help the private party in bidding, contract negotiation, return rate monitoring and project renegotiation. This study should improve risk sharing and investment returns of urban underground comprehensive pipeline gallery PPP projects.
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SPECIAL SECTION:DISASTER PREVENTION AND MITIGATION
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EOC model: A conceptual model to analyze emergencies
QIAN Jing, LIU Yi
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 259-265. DOI: 10.16511/j.cnki.qhdxxb.2021.22.040
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Emergencies include various types of information that have very complex internal logic structures. This paper presents an emergency analysis model, element-object-consequence (EOC) model, for information frames that lack structured information expressions for emergency information analyses. The EOC model uses the basic concepts of "element", "object", "consequence", "environment", "response and management" and "scenario" to organize the emergency information. The model then uses conceptual and mathematical analyses and presentations with frameworks based on these six concepts. A case study shows that this model provides analyses, expressions and storage of information from unstructured, semi-structured and structured sources, as well as qualitative and quantitative presentations of the entire emergency development process.
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Urban resilience assessment model for waterlogging disasters and its application
LI Zhengzhao, FU Dafang, WANG Junxian, MIN Kedong, ZHANG Junyu
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 266-276. DOI: 10.16511/j.cnki.qhdxxb.2021.22.037
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In traditional disaster prevention and mitigation analyses, risk assessments for waterlogging disasters usually only consider the infrastructure resilience and natural conditions such as weather and terrain. However, with the development of resilience theory, risk assessment and countermeasures should also include flood prevention and control, emergency responses and post-disaster recovery by the government and residents. This paper presents a set of indicators for evaluating the ability of cities to deal with waterlogging disasters, including 41 basic indicators covering 13 aspects incorporated into a resilience assessment model. The resilience assessment model is then applied to Kunshan, a low lying city in Jiangsu Province, China. The results show that the Kunshan High-Tech Zone has the best resilience and the strongest ability to deal with waterlogging disasters. The index system and model evaluation results are used to develop a targeted improvement strategy for areas with poor resilience to waterlogging disasters.
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Fire locating method based on the convex hull algorithm using partially blocked surveillance cameras
WANG Guanning, CHEN Tao, MI Wenzhong, LIANG Xiaoliang, WANG Rudong
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 277-284. DOI: 10.16511/j.cnki.qhdxxb.2021.22.038
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Video analyses have become very useful in fire investigations. However, the cause of the fire cannot be easily determined when the surveillance cameras are partially blocked. This study analyzes fire locating methods based on the convex hull algorithm when the surveillance cameras are partially blocked. An oil pan pool fire is used to simulate an indoor fire. The charge-couple device (CCD) camera views are partially blocked with the fire scene videos then collected for analyses. The flame videos are collected and preprocessed before analyzing. Then, a convex hull algorithm is used to calculate the pixel coordinates of the flame center. Finally, the monocular vision principle is used to develop a matrix transformation between the world coordinate system and the imaging plane coordinate system to accurately determine the fire location. Tests show that the monocular visual positioning method based on the convex hull algorithm using partially blocked cameras can accurately locate the fire origin as a powerful tool for fire investigations.
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Damage of multi-ribbed composite wall cell after high temperatures
SUN Jing, WU Junyi, ZHAO Xiuli
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 285-293. DOI: 10.16511/j.cnki.qhdxxb.2021.21.038
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The multi-ribbed composite wall structure system is widely used in our country as a kind of energy-saving and shock-absorbing prefabricated building. However, the damage caused byfire reduces the performance of the building and seriously threatens the safety of human life and property. To analyze the performance of the multi-ribbed composite wall cell (MCWC) after high temperatures, MATLAB is used as the platform, the rigid framebar model of elastic-plastic damageis selected, the damage variables after high-temperatureof the subunits in the model are defined, and the local damage value of the wall cell after high temperatures is obtained using the MRCS-Tprogram. Based on the energy method and the local damage value, the general damage index is constructed and used to evaluate the damage. The damage state of MCWC after high temperatures is divided into five stages, and the damage limit value of each stage is given, which provides the basis for damage assessment of MCWC after high temperatures.
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ENERGY AND POWER ENGINEERING
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Numerical study of the effect of fluid properties on droplet impacts
DU Yuxuan, MIN Qi, LI Yanzhi, DU Jiayu
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 294-302. DOI: 10.16511/j.cnki.qhdxxb.2021.21.021
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Previous research on droplet impact dynamics has yielded different results, and the types of fluids studied are not sufficiently diverse. This project numerically modeled droplet impact dynamics with nine kinds of fluids including water, glycerite, silicone oil, and liquid metals at room temperature with viscosities of 1-970 mPa·s and surface tensions of 20-500 mN/m. The phase-field model was used to supplement the data at low Reynolds numbers to explore the applicability of existing theories. The results show that at the beginning of the impact, the existing law for the spread factor,
β
, varying with the dimensionless time,
τ
, is applicable for
Re
>100. The simulation results are consistent with existing theory that the maximum spread factor,
β
max
, scales as
β
max
∝
We
b
in the capillary regime and
β
max
∝
Re
b
in the viscous regime. The effect of wall wettability on the exponent
b
was also analyzed. The minimum center thickness,
h
min
*
, is consistent with the existing theory of
h
min
*
∝
Re
-0.5
only when
We
≥ 10. For
We
< 10, the wall wettability and surface tension strongly influence
h
min
*
. As
Re
tends to 1,
β
max
and
h
min
*
are determined by the initial kinetic energy of droplet and wettability of target surface, but they deviate from the above power function laws.
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Modeling of high pressure hydrogen jet fires
BA Qingxin, ZHAO Mingbin, ZHAO Zeying, HUANG Teng, WANG Jianqiang, LI Xuefang, XIAO Guoping
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 303-311. DOI: 10.16511/j.cnki.qhdxxb.2021.26.022
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Unintended high pressure hydrogen releases and ignition are key scenarios in hydrogen accidents, so they are basic topics of hydrogen safety research. This study modeled three hydrogen fire scenarios including immediate ignition, delayed ignition, and delayed ignition with a barrier wall. The analyses predicted the temperature and pressure distributions for each scenario. The results show that immediate ignition of the released hydrogen resulted in a steady jet fire without significant overpressure. Delayed ignition caused a pressure wave at the ignition location that spread outward. The jet fire for delayed ignition was similar as that for immediate ignition after the fire stabilized. The overpressure decreased with distance from the ignition location. The barrier wall weakened the spread of the pressure waves and the flames with significantly lower overpressures and temperatures behind the wall. Therefore, barrier walls should be used to reduce hazardous areas and shorten separation distances.
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Total industrial park site heat integration with waste heat utilization
JI Feng, SUN Xiaojing, LIU Linlin, DU Jian
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 312-320. DOI: 10.16511/j.cnki.qhdxxb.2021.25.009
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Integrated utility systems, heat exchanger networks (HEN), and refrigeration systems can significantly improve waste heat utilization in industrial parks. This paper presents a programmed approach for total site heat integration. A site heat integration model was developed that includes interactions between the inter-plant HEN, steam system, cooling water system, and absorption cooling (ARC) system and was formulated as a mixed-integer nonlinear programming (MINLP) model. In this model, steam generated from the hot process stream and the utility steam are used as a heat source to heat the cold stream and drive the ARC system. The cooling water and chilled water systems are then used as cooling sources to meet the cooling requirements of the ARC system and the hot stream. Analyses of three plants shows the effect of waste heat utilization on the total energy distribution at the site. The results show that this method significantly reduces the energy consumption and investment by making the overall system configuration more efficient.
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CIVIL ENGINEERING
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Conversion of EICAD route data based on the IFC 4.1 standard
CAO Bingyong, SHI Xinxin
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 321-330. DOI: 10.16511/j.cnki.qhdxxb.2021.22.010
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Route data transfer from 2D to 3D requires an efficient conversion method of the EICAD route data based on industry foundation classes (IFC) 4.1. This paper first analyzes the structural hierarchy and attribute inheritance of the route information model in IFC 4.1 and establishes the mapping relationship between the EICAD parameter data and the IFC curve segment attributes by parsing the EICAD horizontal and vertical curve design files. A C# conversion program is then developed in Visual Studio 2019 with the xBIM toolkit used to verify the conversion method. The results show that the conversion program can convert the EICAD horizontal and vertical curve design files into an IFC route file with the route design information completely restored after importing the IFC file into the building information modeling (BIM) software. This method provides more accurate, effective transfer of the route data between EICAD and the BIM software than the traditional DWG-based interaction mode.
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Reinterpretation of a thermal environment evaluation index “standard effective temperature (SET)”
JI Wenjie, DU Heng, ZHU Yingxin, CAO Bin, LIAN Zhiwei, LIU Shuli, YANG Changzhi
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 331-338. DOI: 10.16511/j.cnki.qhdxxb.2021.22.024
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The standard effective temperature (SET) is an evaluation index based on the two-node thermal physiological model which has been widely used to evaluate thermal comfort. However, the SET is often misused due to misunderstanding the SET equivalent standard environment and differences in some key parameters. This study summarizes the development of the SET index and then reinterprets this index based on Gagge's definition in the 1986 version to correct the misunderstanding of the standard SET environment. In addition, the equivalent standard environment parameters vary with the metabolic rate. The SET calculational method is revised here to correct these problems with guidelines for future applications of the SET index.
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Mechanical behavior of rock-filled concrete with uniaxial compression
WANG Hui, MA Jiajun, ZHOU Hu, HE Shiqin, JIN Feng
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 339-346. DOI: 10.16511/j.cnki.qhdxxb.2021.21.019
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Uniaxial compression tests of rock-filled concrete (RFC) and self-compacting concrete (SCC) were used to measure the complete stress-strain curves for these samples. The results showed the failure modes, peak stresses, peak point strains, elastic moduli and full stress-strain curves of the rock-filled concrete and self-compacting concrete. The results show that the failure interface of the rock-filled concrete is not only the interface between the rockfill aggregate and the self-compacting concrete matrix, but also the fracture surface in the rockfill aggregate itself. During later failure stages, the rockfill structure reduces the slope of the falling section of the stress-strain curve for the rock-filled concrete specimen. The average peak stress of the rock-filled concrete was 29% less than for the self-compacting concrete, the peak strain was 51% less, and the average elastic modulus was 42% more. The shape and position of the rockfill aggregate and the bond between the rockfill aggregate and the self-compacting concrete all affect the mechanical properties of the rock-filled concrete, which makes the test results show the characteristics of large dispersion. The theoretical stress-strain curves for the rock-filled concrete and the self-compacting concrete agree well with the measured curves.
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COMPUTER SCIENCE AND TECHNOLOGY
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Ensemble weighted soft voting truth inference method for crowdsourcing
ZHANG Hua, SHEN Fei, JIANG Shihao, ZHANG Lingjun, XU Hong
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 347-354. DOI: 10.16511/j.cnki.qhdxxb.2021.22.015
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Many truth inference methods have been proposed to improve crowdsourcing quality and to obtain high-quality annotated data. Traditional truth inference uses multiple noisy labels as inputs to deduce the real labels through an aggregation strategy. This paper introduces the features of the instances that most effectively mine the useful information contained in the instances. The probability that a crowdsourcing instance belongs to each category is used to divide the crowd-sourcing dataset. An integrated meta-learning classifier is trained on the new dataset to calculate a similarity degree to get worker weights that show each worker's annotation ability for different instances. Finally, a weighted soft voting method is used to predict the labels. Tests show that this method is superior to existing truth inference algorithms for public and constructed datasets.
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Social network information leakage node probability prediction based on the EDLATrust algorithm
ZHU Weiyi, ZHANG Xueqin, GU Chunhua
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 355-366. DOI: 10.16511/j.cnki.qhdxxb.2021.22.018
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Message forwarding is widely used in social network information systems. However, private information can be leaked without authorization from the information publisher. Privacy information leakage nodes need to be identified to eliminate such security risks. An estimator based distributed learning automata for trust inference (EDLATrust) is developed in this study to infer the trust level between non-directly connected nodes by reducing the number of convergence steps. The EDLATrust algorithm is combined with the XGBoost algorithm to identify privacy leakage in social network by using linear and group information transmission propagation models with three information dissemination characteristics. The algorithm predicts potential links in the information transmission chain and assists predicting information leakage points to improve the information dissemination security in social networks. Tests show that the model can effectively predict information leakage points in the information transmission chain for three real social network data sets to protect user privacy.
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MECHANICAL ENGINEERING
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Research and verification of welding heat source parameter optimization model
ZHANG Hongwei, GUI Liangjin, FAN Zijie
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 367-373. DOI: 10.16511/j.cnki.qhdxxb.2021.25.011
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Accurate simulations of the temperature field during welding are important for analyzing welding residual stresses and material deformation. The welding temperature field is directly related to the shape parameters of the heat source. However, the heat source shape parameter determination is generally a trial and error process with the efficiency and accuracy highly dependent on the researcher experience. This paper presents an optimization model for determining the heat source parameters during welding which can be used to estimate the shape parameters of various heat sources. Finite element simulations with the optimized parameters compared well with experimental data. The results show that this optimization method reduces the cost of repeated modeling to obtain the optimal heat source parameters, which also reduces the influence of the researchers' experience on the efficiency and accuracy of welding temperature simulations.
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Influence of stirring head structure on the defect formation mechanism in friction stir welding
YANG Zhiyong, LI Wupeng, ZHANG Yu, LI Zhiqiang, LI Weijing
Journal of Tsinghua University(Science and Technology). 2022,
62
(2): 374-384. DOI: 10.16511/j.cnki.qhdxxb.2021.22.039
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The friction stir welding stirring head structure and welding process parameters lead to different welding heat inputs and material flow behaviors that result in different types of weld defects. This study simulated friction stir welding of A7N01 material using the Deform software. The model was verified by comparing with measured temperatures and observed defects in welding tests. The model was then used to investigate the influence of three kinds of stirring heads on the weld defect formation. The material particle tangential filling speeds varied with depth for different stiring heads. The circular stirring head mostly created tunnel-type and furrow-type defects, while the plane stirring heads mostly caused half-tunnel-and-half-furrow-type defects. Different process parameters for the same stirring head resulted in different types of defects in the advancing side of the weld. A two-dimensional process parameter selection window was then developed to select conditions that would prevent typical welding defects for each stirring head. The process parameter range is wider for the plane stirring head than for the circular stirring head for friction stir welding.
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