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Background Error Statistics for Aerosol Variables from WRF/Chem Predictions in Southern California
Zengliang Zang,Zilong Hao,Xiaobin Pan,Zhijin Li,Dan Chen,Li Zhang,Qinbin Li 한국기상학회 2015 Asia-Pacific Journal of Atmospheric Sciences Vol.51 No.2
Background error covariance (BEC) is crucial in data assimilation. This paper addresses the multivariate BEC associated with black carbon, organic carbon, nitrates, sulfates, and other constituents of aerosol species. These aerosol species are modeled and predicted using the Model for Simulating Aerosol Interactions and Chemistry scheme (MOSAIC) in the Weather Research and Forecasting/Chemistry (WRF/Chem) model at a resolution of 4 km in Southern California. The BEC is estimated from the differences between the 36-hour and 12-hour forecasts using the NMC method. The results indicated that the maximum background error standard deviation is associated with nitrate and is larger than that of black carbon, organic carbon, and sulfate. The horizontal and vertical scale of the correlation of nitrate is much smaller than that of other species. A significant cross-correlation is found between the species of black carbon and organic carbon. The cross-correlations between nitrate and other variables are relatively smaller and exhibit a relatively smaller length scale. Single observation data assimilation experiments are performed to illustrate the effect of the BEC on analysis increments.
Data-Driven Quadratic Optimization for Tracking Problems with Application to a Tray Indexing System
Zilong Cheng,Jun Ma,Xiaocong Li,Xiaoxue Zhang,Tong Heng Lee 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10
Iterative Feedback Tuning (IFT) algorithm explores the correlation between the cost function and the parameters of the controller. It introduces one data-driven approach to derive the gradient of the cost function with respect to the controller parameters and provides an iterative numerical method for the controller parameters optimization. However, classical IFT algorithms require three experiments to be conducted at one iteration, and one special experiment is included in the three experiments. That means the reference signal is changed during the iteration because of the special experiment, which restricts the application of the IFT algorithm in many areas. Besides, in many process control applications with long duration, IFT algorithm is much more time-consuming than many other tuning algorithms. In this paper, a novel IFT algorithm is proposed. For each iteration, no special experiment is required, which means parameters of the controller can be tuned when the system is running normally. Simulation results on a tray indexing system demonstrate the high performance and applicability of this algorithm.
Application Research on Mechanical Strength and Durability of Porous Basalt Concrete
Zhu, Yuelei,Li, Jingchun,Zhu, He,Jin, Long,Ren, Qifang,Ding, Yi,Li, Jinpeng,Sun, Qiqi,Wu, Zilong,Ma, Rui,Oh, Won-Chun Materials Research Society of Korea 2022 한국재료학회지 Vol.32 No.3
Porous basalt aggregate is commonly used in roadbed engineering, but its application in concrete has rarely been studied. This paper studies the application of porous basalt in concrete. Porous basalt aggregate is assessed for its effects on mechanical strength and durability of prepared C50 concrete; because it has a hole structure, porous basalt aggregate is known for its porosity, and porous basalt aggregates can be made full of water through changing the content of saturated basalt; after full-water condition is achieved in porous basalt aggregate mixture of C50 concrete, we discuss its mechanical properties and durability. The effects of C50 concrete prepared with basalt aggregate on the compressive strength, water absorption, and electric flux of concrete specimens of different ages were studied through experiments, and the effects of different replacement rates of saturated porous basalt aggregate on the properties of concrete were also studied. The results show that porous basalt aggregate can be prepared as C50 concrete. For early saturated porous basalt aggregate concrete, its compressive strength decreases with the increase of the replacement rate of saturated aggregate; this occurs up to concrete curing at 28 d, when the replacement rate of saturated basalt aggregate is greater than or equal to 40 %. The compressive strength of concrete increases with the increase of the replacement rate of saturated aggregate. The 28 d electric flux decreases with the increase of the replacement rate of saturated aggregate, indicating that saturated porous basalt aggregate can improve the chloride ion permeability resistance of concrete in later stages.
A Sobel Operator Combined with Patch Statistics Algorithm for Fabric Defect Detection
( Jiein Jiang ),( Zilong Jin ),( Boheng Wang ),( Li Ma ),( Yan Cui ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.2
In the production of industrial fabric, it needs automatic real-time system to detect defects on the fabric for assuring the defect-free products flow to the market. At present, many visual-based methods are designed for detecting the fabric defects, but they usually lead to high false alarm. Base on this reason, we propose a Sobel operator combined with patch statistics (SOPS) algorithm for defects detection. First, we describe the defect detection model. mean filter is applied to preprocess the acquired image. Then, Sobel operator (SO) is applied to deal with the defect image, and we can get a coarse binary image. Finally, the binary image can be divided into many patches. For a given patch, a threshold is used to decide whether the patch is defect-free or not. Finally, a new image will be reconstructed, and we did a loop for the reconstructed image to suppress defects noise. Experiments show that the proposed SOPS algorithm is effective.
Experimental study on bearing capacity of PFCC column-RC beam joint reinforced with CST
Ping Wu,Dongang Li,Feng Yu,Yuan Fang,Guosheng Xiang,Zilong Li 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.1
An experimental study of eleven PVC-FRP Confined Concrete (PFCC) column-Reinforced Concrete (RC) beam joints reinforced with Core Steel Tube (CST) under axial compression is carried out. All specimens are designed in accordance with the principle of “weak column and strong joint”. The influences of FRP strips spacing, length and steel ratio of CST, height and stirrup ratio of joint on mechanical behavior are investigated. As the design anticipated, all specimens are destroyed by column failure. The failure mode of PFCC column-RC beam joint reinforced with CST is the yielding of longitudinal steel bars, CST and stirrups of column as well as the fracture of FRP strips and PVC tube. The ultimate bearing capacity decreases as FRP strips spacing or joint height increases. The effects of other three studied parameters on ultimate bearing capacity are not obvious. The strain development rules of longitudinal steel bars, PVC tube, FRP strips, column stirrups and CST are revealed. The effects of various studied parameters on stiffness are also examined. Additionally, an influence coefficient of joint height is introduced based on the regression analysis of test data, a theoretical formula for predicting bearing capacity is proposed and it agrees well with test data.
Study on preparation of inorganic binder stabilized material with large dosage of phosphogypsum
Sun Qiqi,Tao Liangjing,Li Xin,Xu Wei,Yao Shuo,Li Jinpeng,Ren Qi-Fang,Chen Yue’e,Xu Chunshan,Wu Zilong,Zhu Yuelei,Ding Yi,오원춘 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.6
With the rapid development of the phosphorus chemical industry, a large amount of phosphogypsum (PG) is discharged. The impurities in PG pollute the surrounding soil, the groundwater and the air in the long-term storage. In this paper, PG as the main raw material is used to study the stable material of inorganic binder in the condition of large dosage of PG. With PG and graded gravel as stabilized materials, and cement and fly ash as binder, materials are mixed to determine the influence of PG ratio and the amount of activator on the mixture. The results show that the mechanical strength of the mixture increased first and then decreased with the increase in the proportion of PG replacing graded gravel in the mixture. The activator significantly improves the properties of the material system and makes a significant contribution to the curing of PG. The best ratio of pretreated PG: cement: fly ash: aggregate is 50:6:5:39. The amount of activator added by the external mixing method is 0.3%, which can make the unconfined compressive strength reach 4.1 MPa after 7d. Finally, water-soluble phosphorus leaching experiment is conducted for all the samples. The results show that phosphorus leaching is so little that no secondary pollution of the environment is caused.
Chao Zhang,Zhichao Lai,Xiaoqiang Yang,Qiang Li,Zilong Zhang,Xindi Fu 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.1
Accidental cable failure may occur for complicated suspend-dome structures, resulting in the dynamic impact effect on structures. This study presents simplified analysis methods for evaluating suspend-dome structures when sudden cable failure occurs. An implicit analysis method of improved alternative load path (IAM-IAP) was employed to simply simulate the cable failure process of the beam-string structure. The IAM-IAP was also validated by comparing the calculated results with the existing test results for the truss string structure. The parameters of the cable failure process (i.e., failure time, failure path, and damping ratio) were analyzed, and suitable values were recommended. Based on the IAM-IAP, a finite element model of multi-loop cable-string suspend-dome structure (MCSS) was established and benchmarked by verifying the static responses during construction. Dynamic responses (i.e., time histories, displacements, axial forces, and dynamic amplification factors) of MCSS were systematically investigated. The dynamic amplification factor may be larger than 2, exceeding the suggested value of existing specifications. A static equivalent method with reasonable prediction accuracy was also proposed to simply assess the dynamic responses of suspend-dome structures subjected to sudden cable failure.