Table of Content

30 April 2020, Volume 26 Issue 2

Previous Issue    Next Issue

Invited Review

Research progress on the mechanical properties of threaded connections for oil country tubular goods

DI Qinfeng, WANG Nan, CHEN Feng, WANG Wenchang, NIU Xinming, ZHANG Jincheng

2020, 26(2):  163-180.  doi:10.12066/j.issn.1007-2861.2208

Asbtract ( 1000 )   HTML ( 546)   PDF (2790KB) ( 190 )  

Figures and Tables | References | Related Articles | Metrics

With the increase in reservoir depth, the drilling and production conditions under which oil and gas are processed are becoming increasingly severe. Complex loads, including huge tension, significant compression, considerable bending, high internal and external pressure, and high temperature, cause the frequent failure of oil country tubular goods (OCTG). Threaded connection failure is one of the main failures encountered in oil fields, and increasing attention has been paid to the development of threaded connections with improved strength and sealing performance. As one of the vital works in the development of premium threaded connections, the analysis methodology governing the mechanical properties of threaded connections needs to be solved urgently. In this paper, the research progress concerning the mechanical properties of threaded connections is described from the aspects of three methods: analytical, experimental, and numerical simulation. The mechanical properties, test methods, equipments, and numerical simulation methods of OCTG threaded connections are described. Based on the summary and analysis of the shortcomings of the current works, the new future research direction for threaded connections has been suggested.

Research Articles

Estimation method of moving average model with missing data

CHEN Bo, HE Youhua

2020, 26(2):  181-188.  doi:10.12066/j.issn.1007-2861.2035

Asbtract ( 1117 )   HTML ( 354)   PDF (860KB) ( 120 )  

Figures and Tables | References | Related Articles | Metrics

Based on the EM algorithm for model parameter estimation, this paper examines the $q$-order moving average model with missing data, aiming at figuring out the estimation of missing data and its covariance matrix. The effectiveness of the proposed algorithm is verified by numerical simulation which shows the following results: the mean square error of the model parameter estimation grows with the increase of the model order, the length of model characteristic roots and the proportion of missing data respectively. In addition, the value decreases when the length of sequence increases. The mean square error of missing data grows with the increase of the model order and the length of model characteristic roots. However, it is not sensitive to the length of the sequence and the proportion of missing data. An instance illustrates that the method estimates the model well in the case of missing data.

Factorization of xⁿ-1 over finite field F_p

DING Yang, WANG Yongchao

2020, 26(2):  189-196.  doi:10.12066/j.issn.1007-2861.2026

Asbtract ( 825 )   HTML ( 152)   PDF (266KB) ( 186 )  

References | Related Articles | Metrics

Let p be an odd prime number. This paper presents an algorithm for the factorization of xⁿ-1 over prime field F_p, where n=d(p+1), d|(p-1) and d＜p-1. As is suggested, the factorization problem can be solved by Dickson polynomials based on a primitive polynomial over F_p. Some examples are provided for the explanation of this algorithm.

Qualitative analysis of the asymmetric I-V curve in STM molecular junctions

QIAN Lijiang, LI Weiju, ZHANG Yibing, CHEN Jingzhe

2020, 26(2):  197-206.  doi:10.12066/j.issn.1007-2861.2028

Asbtract ( 974 )   HTML ( 192)   PDF (1061KB) ( 120 )  

Figures and Tables | References | Related Articles | Metrics

Quantum transport properties of molecular devices are mostly measured by scanning tunneling microscopy (STM). The results show abnormal features such as asymmetric I-V (AIV) curve or negative differential conductance (NDC), which are not to be observed in the case of common macroscopic devices. Based on finite element method and parameter models, the Hamiltonian of a sample system with a local state is presented. The non-equilibrium Green's function method is used to calculate the electron density and the tunneling current of the device after self-consistent convergence. After investigating the effects of different parameters, including the electrode coupling strength, molecular energy level, local energy level, the influences of the local states and geometrical asymmetry on the transport properties of molecular devices have been analyzed. It is concluded that the intrinsic region of AIV and NDC in STM related molecular devices experiments is the offset of the local states in the tip.

Effects of HSP content on microstructure and mechanical properties of EVA foamed materials

LIU Li, TU Duoxiang

2020, 26(2):  207-215.  doi:10.12066/j.issn.1007-2861.2030

Asbtract ( 886 )   HTML ( 25)   PDF (1215KB) ( 39 )  

Figures and Tables | References | Related Articles | Metrics

A series of ethylene-vinyl acetate (EVA)/hemp stem powder (HSP) foamed materials with different ratios were prepared by following the injection molding process. The morphology of HSP and EVA/HSP foamed materials were observed by scanning electron microscopy (SEM). The melt strength and storage modulus of EVA/HSP blends were tested by Hacker torque rheometer and rotation rheometer. The effects of HSP content on the mechanical properties of EVA/HSP foamed materials were also explored. The results showed that the surface of HSP contained a large number of cracks and grooves, and that with the increase of HSP content, the cell sizes of EVA/HSP foamed materials decreased from 79.64 um to 69.85 um, and the melt strength of EVA/HSP blends increased from 3.7 Nm to 4.5 Nm, the density, hardness, tensile strength and rebound resilience of EVA/HSP foamed materials decreased, and its elongation at break and compression became improved.

Induced solidification of liquid Al from molecular dynamics simulation

YU Ronggang, LAI Qinmei, WANG Hao, WU Yongquan

2020, 26(2):  216-226.  doi:10.12066/j.issn.1007-2861.2038

Asbtract ( 716 )   HTML ( 29)   PDF (1109KB) ( 94 )  

Figures and Tables | References | Related Articles | Metrics

Molecular dynamics (MD) simulation was applied to analyze the solidification of liquid Al induced by embedded solid nanoparticles with radii ranging from 0.37 to 2.4 nm. It was found that the critical temperature was proportional to the inverse of the nucleus radius, i.e., Gibbs-Thomson (G-T) effect, through which the G-T coefficient Γ and the bulk melting temperature T_m^bulk were obtained, 1.41.4*10^-7 Km and (985.36±11.25) K, respectively. The solid-liquid interfacial energy which was estimated (140.35±9.05)mJ/m² from Γ, was very close to the calculated 149 mJ/m² by capillary fluctuation method. It proved again that Turnbull underestimated this quantity experimentally (93 mJ/m²). The critical failure radius was extrapolated to be 0.91 nm. Meanwhile, the corresponding system temperature had reached the lower limit for the critical temperature, under which the system could be spontaneously nucleated, and the incubation time was somewhat random. Besides, the microstructure was characterized by the metastable cross stacking faults. When the embedded nucleus could serve as the nucleation core, the incubation time increased with increasing embedded nucleus radius. However, the growth rate decreased separately with the increasing embedded nucleus radius. The microstructure adopted the relatively stable lamellar structure.

Analysis of cembratriene-diols in tobacco by LC-GC/MS

HUANG Zhi, BI Yanjiu, SHA Yunfei, XIE Wenyan, WU Da, LIU Baizhan, LIU Taiang

2020, 26(2):  227-233.  doi:10.12066/j.issn.1007-2861.2078

Asbtract ( 1269 )   HTML ( 36)   PDF (574KB) ( 196 )  

Figures and Tables | References | Related Articles | Metrics

Cembratriene-diols are the precursors of important neutral aroma components and their derivatives, which affect significantly the aroma style and tobacco quality. In this study, a method of in-series combination of ultrasound-assisted extraction and online liquid chromatography-gas chromatography/mass spectrometry (LC-GC/MS) was constructed for the analysis of cembratriene-diols in tobacco. Cembratriene-diols were first extracted by ultrasound-assisted extraction and then on-line clean-up and analysis by online LC-GC/MS system. The pretreatment was highly efficient and easy-handling. Good recovery and reproducibility had also been achieved. This method was subsequently applied to the analysis of cembratriene-diols extracted from different regions of tobacco leaves. The satisfactory performance indicated that this strategy was suitable for the high-throughput analysis of cembratriene-diols in tobacco.

Anti-penetration capability of SiC/UHMWPE composite armour plates through experimental and numerical simulation

LIU Di, XIAO Yi, JIANG Xuwei, LI Hong, YU Mingming, REN Musu, SUN Jinliang

2020, 26(2):  234-243.  doi:10.12066/j.issn.1007-2861.2037

Asbtract ( 1099 )   HTML ( 44)   PDF (805KB) ( 167 )  

Figures and Tables | References | Related Articles | Metrics

With the hard-soft structure of silicon carbide (SiC) ceramics with ultra-high molecular weight polyethylene (UHMWPE), four light-weight composite armour plates for different ratios have been designed. Tests on the penetration capability of several different types of small-bore bullets impacting each composite armour plate have been conducted, and numerical simulation analysis through the LS-DYNA program for the penetration process has been carried out as well. The test results and the numerical simulation results are found to be in good agreement. This indicates that the light-weight composite armour plates of hard-soft structure can effectively block the penetration from 7.62 and 5.8 mm small-bore bullets and greatly improves the protection capability.

A new method for measuring surface tension—real sphere bubble method

GUO Jie, YU Zhongda, ZHENG Shaobo, RYO Moriyasu, HIROMICHI Takebe, KUSUHIRO Mukai

2020, 26(2):  244-254.  doi:10.12066/j.issn.1007-2861.2024

Asbtract ( 1093 )   HTML ( 30)   PDF (1062KB) ( 210 )  

Figures and Tables | References | Related Articles | Metrics

A new device for measuring surface tension was designed, and the surface tension of liquid was calculated through real-time measurement of the radius and the differential pressure between inside and outside of the liquid bubble. This new method of measuring liquid surface tension is known as real sphere bubble method (RSBM). In this paper, the surface tension of sodium dodecyl sulfate (SDS) solutions is measured. The results are consistent with the literature. The absolute accuracy of this apparatus is 98.2%. In addition, ΔP_m is the maximum differential pressure required for rapid growth of bubbles formed by SDS solutions. The difficult level of foaming a liquid bubble and the size of a bubble is quantitatively analyzed by detecting ΔP_m for sudden bubble growth and the change of surface area over time.

Preparation of propionic acid and lactic acid intercalated LDHs and comparison of loading carbon content

SHENG Liang, JIANG Li, YE Min, LIU Jianyong, QIAN Guangren, LI Yuyou, XU Zhiping

2020, 26(2):  255-262.  doi:10.12066/j.issn.1007-2861.2023

Asbtract ( 780 )   HTML ( 361)   PDF (718KB) ( 77 )  

Figures and Tables | References | Related Articles | Metrics

Layered double hydroxides (LDHs) intercalated with propionate anions, lactate anions and mixed acid were synthesized with co-precipitation method under the artificial system. Results of X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis indicated that the three LDHs samples were coincident with the structure of Ni/Fe-LDH. Additionally, lactate anions and propionate anions were successfully intercalated into LDHs. The loading carbon contents of propionic acid in C₂H₅COO-LDH and C₂H₅COO-C₃H₅O₃-LDH were (2.38±0.07) and (2.27±0.05) mmol/g LDH, respectively, while the loading carbon contents of lactic acid in C₂H₅COO-LDH and C₂H₅COO-C₃H₅O₃-LDH were (1.57±0.04) and (0.84±0.03) mmol/g LDH, respectively, indicating that propionate anion was more competitive than lactate anion to be intercalated into LDHs.

Based on the variation of black carbon in PM_2.5 to observe pollution episode in winter Shanghai

CHEN Qi, FANG Yin, FENG Yanli, ZHANG Fan, ZHU Wenjie, WANG Wu, CHEN Yingjun

2020, 26(2):  263-274.  doi:10.12066/j.issn.1007-2861.2025

Asbtract ( 826 )   HTML ( 21)   PDF (1349KB) ( 57 )  

Figures and Tables | References | Related Articles | Metrics

During the period between November 29th and December 9th in 2016,two air pollution episodes occurred in Shanghai, with the highesthourly concentration of PM_2.5 reaching 119 and 179 ug/m³, respectively. The concentration of black carbon (BC) wasobserved, and fine particle matter was sampled and compositions suchas organic carbon (OC), element carbon (EC), water-soluble ions andelement were analyzed in two pollution episodes to observe thecomposition and source of PM_2.5. Investigation results showedthat in two pollution episodes, the average concentrations of PM_2.5 in pollution stage were 4.2 and 3.9 times of that inclean stage, respectively. The average concentrations of BC inpollution stage were 1.6 and 1.9 times of that in clean stage. Thehighest BC hourly concentration and the proportion of BC in PM_2.5 during pollution episodes were 8.94 ug/m³ and22.0%. The average proportions of BC in PM_2.5 in clean stagewere 11.8% and 7.5%, respectively, which were higher than theproportion in pollution stage (4.4% and 3.7%). The averageproportions of secondary pollutants in PM_2.5 were 41.8% and31.9%, respectively. The average proportions of secondary organiccarbon (SOC) in OC were 42.5% and 34.9%, respectively. Coalcombustion, vehicles, boats and biomass burning contributedsignificantly to the pollution episodes.

Pollution sources and distribution characteristics of pathogenic microorganisms in landscape rivers

XU Xiaoxuan, KANG Lijuan, YE Jianfeng, JIAO Zheng, PU Xianjuan

2020, 26(2):  275-282.  doi:10.12066/j.issn.1007-2861.2036

Asbtract ( 822 )   HTML ( 33)   PDF (1144KB) ( 100 )  

Figures and Tables | References | Related Articles | Metrics

It took three landscape river sections in Xuhui District, Shanghai as an example for the investigation of the distribution and main sources of pathogenic microorganisms in landscape rivers under different weather scenarios. The results showed that the average concentration of fecal coliform was 1.31*10⁵  MPN/100 mL on sunny days and 2.49*10⁵ MPN/100 mL on rainy days with River 1. The average concentrations of fecal coliform in River 2 and River 3 on sunny days and rainy days remained at 10$^{4}$ MPN/100 mL. The average concentrations of coliform were two orders of magnitude in all 3 rivers. River 1 was 3.6*10³ CFU/mL, and River 2 and River 3 were 29 and 98 CFU/mL respectively. On rainy days, the average concentration of coliform was two orders of magnitude as same as that on sunny days. The concentrations of fecal coliform and coliform were increased in both rainfall and rain water pump stations, but the increase of coliform was significantly higher than that of fecal coliform. Clearly, rainfall is one of the main sources of pathogenic microorganisms in landscape river. Although human beings do not usually have direct contact with the landscape rivers, there are still some health risks. It is necessary to strengthen the monitoring and control of the pollution caused by pathogenic microorganisms.

Fine-grained image classification of succulents with convolutions

HUANG Jiabao, ZHU Yonghua, ZHOU Jiting, GAO Wenjing

2020, 26(2):  283-291.  doi:10.12066/j.issn.1007-2861.2029

Asbtract ( 836 )   HTML ( 1397)   PDF (981KB) ( 172 )  

Figures and Tables | References | Related Articles | Metrics

Succulents recognition is an important task in plants identification and management, and domain-specific features and large datasets are used. Due to the absence of an existing succulents' dataset, a large number of pictures need to be collected. This paper addresses the issue of fine-grained image classification of succulent plants. Both supervised and weakly supervised fine-tuning of AlexNet and GoogLeNet training on original dataset were imple mented, trained and tested for the task of identifying the class of succulents from various viewpoints, backgrounds, light effects and growth stages. Results showed that supervised fine-tuning GoogLeNet improved the performance, and the accuracy rate could be as high as 96.7${\%}$.

Technology innovation risk evaluation based on interval value intuitionistic fuzzy sets

TIAN Yongchao, YU Liying

2020, 26(2):  292-300.  doi:10.12066/j.issn.1007-2861.2034

Asbtract ( 728 )   HTML ( 24)   PDF (505KB) ( 99 )  

Figures and Tables | References | Related Articles | Metrics

Reducing the risks of technological innovation in enterprises is the key to improving the technological innovation performance. This paper first identifies 18 potential risks based on the six-stage model of technological innovation, and then constructs the fuzzy failure mode and effect analysis (FMEA) method applied to the risk assessment of technological innovation based on the interval value intuitionistic fuzzy set. The method evaluates the severity, occurrence and detection of each potential risk by the interval valued intuitionistic fuzzy set. Risk priority numbers are obtained and sorted by the technique for order preference by similarity to ideal solution (TOPSIS)-based nonlinear programming solution, which can be used as a basis for prioritizing potential risks. At last, the feasibility of the fuzzy FMEA method is verified by an example of D-company's seat development project.

Shear bearing capacity for concrete beams with FRP reinforcement

ZHANG Zhimei, CHEN Gang, WANG Zhuo

2020, 26(2):  301-310.  doi:10.12066/j.issn.1007-2861.2027

Asbtract ( 410 )   HTML ( 17)   PDF (1244KB) ( 55 )  

Figures and Tables | References | Related Articles | Metrics

171 test beams reinforced with fiber-reinforced polymer (FRP) bars including with and without FRP stirrups were analyzed by using shear bearing capacity's formulas recommended by the Technical Code for Infrastructure Application of FRP Composites (GB 50608—2010). By comparing each beam's predicted shear strength with its corresponding experimental value, the result showed that the method adopted by the Code was highly conservative. Therefore, main factors affecting the shear capacity of FRP reinforced concrete members with shear reinforcement were analyzed by adopting the grey relational analysis. The results showed that the most important factor was effective depth of the cross section, followed by longitudinal reinforcement ratio, concrete compressive strength, the shear span ratio and so on. Accordingly, it was analyzed that the formulas in the Code underestimated the effect of effective depth of the cross section and ignored its impact on shear span ratio and so on. The formulas were revised on the basis of previous analyses and their rationality verified by using aforementioned 171 beams test data. Compared with the unrevised provision, the mean of ratio of the test to the predicted shear strength of the beams without shear reinforcement went from 4.78 down to 1.49, whereas in the case of those beams with stirrups the figure went from 2.18 down to 1.40.