Experimental and Numerical Study on Complex Multi-planar Welded Tubular Joints in Umbrella-Type Space Trusses with Long Overhangs

Jinfeng Jiao,Xiao Ma,Honggang Lei,Y. Frank Chen 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.5

A test rig with multi-functional purposes was specifi cally designed and manufactured to study the behavior of multi-planar welded tubular joints subjected to multi-planar concurrent axial loading. An experimental investigation was conducted on full-scale welded tubular joints with each consisting of one chord and eight braces under monotonic loading conditions. Two pairs or four representative specimens (two specimens for each joint type) were tested, in which each pair was reinforced with two kinds of diff erent internal stiff eners at the intersections between the chords using welded rectangular hollow steel sections (RHSSs) and the braces using rolled circular hollow steel sections (CHSSs) and welded RHSSs. The eff ects of different internal stiff eners at the chord–brace intersection on the load capacity of joints under concurrent multi-planar axial compression/tension are discussed. The test results of joint strengths, failure modes, and load–stress curves are presented. Finite element analyses were performed to verify the experimental results. The study results show that the two diff erent joint types with the internal stiff eners at the chord–brace intersection under axial compression/tension signifi cantly increase the corresponding ultimate strength to far exceed the usual design strength. The load carrying capacity of welded tubular joints decreases with a higher degree of the manufacturing imperfection in individual braces at the tubular joints. Furthermore, the interaction eff ect of the concurrent axial loading applied at the welded tubular joint on member stress is apparent.

Adaption strategy of up-flow anaerobic sludge blanket reactor on tetracycline stress during tetracycline antibiotic wastewater treatment

Jinfeng Zhang,Guanyi Chen,Qin Zhang,Yi Luo,Chunsong Wu,Songyan Qin 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.3

Tetracycline antibiotic wastewater with high chemical oxygen demand (COD) concentration and containing bio-refractory compounds was investigated in a lab-scale up-flow anaerobic sludge blanket (UASB) and anoxic-oxic (A/O) reactor. Specific methanogenic activity (SMA) was determined to reveal the inhibition levels of methane production and volatile fatty acid (VFA) accumulation. The results showed that microorganisms can adapt to tetracycline or oxytetracycline when the concentration of antibiotics is less than 400 mg/L. Acetic acid, propanoic acid, and n-butyric acid accounted for more than 90% of VFA with increasing antibiotic concentration from 50 mg/L to 600 mg/L. During the 215 d of operation, the concentration of tetracycline antibiotic increased from 0 to 95 mg/L, and the COD concentration from 3,500 to 6,500 mg/L. The average COD and tetracycline antibiotic removal rates of the reactors were maintained above 90%. The methane production of the UASB reactor achieved 0.32 L/g COD. VFA accumulation was observed when tetracycline antibiotic concentration increased to 47.5 mg/L. The sludge granule diameter increased from 0–300 μm to 300–1,500 μm during the operation. Rod-shaped and coccus-shaped organisms with pores and internal channels on the granule surface were observed using scanning electron microscopy. In the internal space, methanogenic filamentous bacteria constitute a rock-steady structure.

Purification of pickling wastewater from the steel industry using membrane filters: Performance and membrane fouling

Jinfeng Zhang,Guanyi Chen,Yanning Ma,Miao Xu,Songyan Qin,Xiaoliang Liu,Haijun Feng,Lian Hou 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.1

A new technique for treating pickling wastewater discharged from the steel industry using membrane filters was developed and membrane fouling was characterized in a full scale membrane filter. The morphological and chemical properties were examined through scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma optical emission spectroscopy (ICP-OES) etc. The results showed that inorganic elements such as phosphates, chlorides, and sulfates were severely blocked in membrane surfaces and pores. The porosity, permeability, hydrophilic contact angle, and surface charge capacity of fouled membranes were all lower than those of new membranes, while the optimal neutralization reaction pH region for fouled membranes shifted and narrowed. Charge neutralization is a critical reason to membrane fouling. By increasing the Zeta potential of the pickling wastewater, the membrane fouling could be controlled. This method is proven to effectively improve the separation property of precipitates after pickling wastewater was neutralized. Moreover, Neutralization helped to reduce the unit number of treatment processes. This investigation could assist in obtaining a better understanding of the fouling properties and behavior in the full-scale membrane filters in the pickling wastewater treatment.

Existence of solutions for fractional $p\&q$-Kirchhoff system in unbounded domain

Jinfeng Bao,Caisheng Chen 대한수학회 2018 대한수학회보 Vol.55 No.5

In this paper, we investigate the fractional $p\&q$-Kirchhoff type system $$\left\{ \begin{array}{l} M_1([u]^p_{s,p})(-\Delta)_p^su+V_1(x)|u|^{p-2}u\\ \quad=\ell k^{-1}F_u(x,u,v)+\lambda a(x)|u|^{m-2}u,\quad x\in\Omega,\\ M_2([u]^q_{s,q})(-\Delta)_q^sv+V_2(x)|v|^{q-2}v\\ \quad=\ell k^{-1}F_v(x,u,v)+\mu a(x)|v|^{m-2}v,\quad\ x\in\Omega,\\ u\,=v\,=0,\qquad\qquad\qquad\qquad\qquad\qquad\ \ x\in\partial\Omega, \end{array} \right.$$ where $\Omega\subset \mathbb{R}^N$ is an unbounded domain with smooth boundary $\partial\Omega$, and $0<s<1<p\leq q$ and $sq<N,$ $\lambda,\mu>0$, $1<m\leq k<p_s^*$, $\ell\in\mathbb R,$ while $[u]^t_{s,t}$ denotes the Gagliardo semi-norm given in (\ref{1.2}) below. $V_1(x), V_2(x), a(x): \R^N\to (0,\infty)$ are three positive weights, $M_1, M_2$ are continuous and positive functions in $\R^+$. Using variational methods, we prove existence of infinitely many high-energy solutions for the above system.

Experimental Research and Finite Element Analysis on Structural Stability of Disc-Buckle Type Formwork Support

Jinfeng Dong,Haiqing Liu,Shengyong Xia,Yang Cheng,Ming Lei,Zimu Chen 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.3

In order to study the structural stability of the disc-buckle type formwork support, the multi-parameter experimental analysis of the disc-buckle type formwork support structure was carried out by using experimental and fi nite element analysis method. The infl uence parameters of working conditions, lift height, diagonal bracing and sleeve on the structural stability bearing capacity was mainly considered. The regularity of the buckling direction of the vertical pole, the stress at each typical position on the vertical pole and the axial force of the vertical pole was studied based on the experimental results. Based on the characteristics of semi-rigid connection joints, the correctness of the experimental results was verifi ed by fi nite element analysis, and the results show that reducing lift height and arranging diagonal bracing have remarkable infl uence on improving the structural stability bearing capacity. The usage of sleeves has little infl uence on the structural stability, and the corner pole was the worst position of the overall structural stability. The factors of working conditions and diagonal bracing have the remarkable infl uence on the buckling direction of the vertical pole. The factor of working condition has the most obvious infl uence on the stress uniformity of the vertical pole. The axial force of the vertical pole in the disc-buckle type formwork support structure presented a relatively uniform state from bottom to top in the loading process. The arrangement of diagonal bracing and the usage of sleeves have an infl uence on the uniformity of the axial force of the vertical pole. Compared with the fi nite element results, the error of the structural stability bearing capacity was within 6%, indicated that the fi nite element can accurately simulate the structural stability bearing capacity.

Neural adaptive pointing control of a moving tank gun with lumped uncertainties based on dynamic simulation

Yu Chen,Youhui Cai,Guolai Yang,Honggen Zhou,Jinfeng Liu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

This study focuses on the pointing control problem of a moving tank gun. Model uncertainty and foundation vibration, which may be nonlinear, coupled, or time-varying but bounded, are considered. First, the electrohydraulic servo system of a vertical stabilizer is constructed as a nonlinear dynamic system with lumped uncertainties. Second, a neural adaptive controller is proposed to improve the control performance of the vertical stabilizer. A backpropagation neural network is introduced to compensate for the uncertainties, and its weight and threshold values are self-tuned online. Third, a co-simulation model of the moving tank is established. Dynamic simulation verifies that the proposed controller exhibits better performance than typical controllers. Finally, the influence of hull foundation vibration on the proposed controller is analyzed. The pointing accuracy of a moving tank gun is verified to be controlled effectively by the proposed controller under different driving conditions. This work combines control theory with multi-body dynamics to provide a feasible solution for the pointing control problem of a moving tank with model uncertainty and foundation vibration.

EXISTENCE OF SOLUTIONS FOR FRACTIONAL p&q-KIRCHHOFF SYSTEM IN UNBOUNDED DOMAIN

Bao, Jinfeng,Chen, Caisheng Korean Mathematical Society 2018 대한수학회보 Vol.55 No.5

In this paper, we investigate the fractional p&q-Kirchhoff type system $$\{M_1([u]^p_{s,p})(-{\Delta})^s_pu+V_1(x){\mid}u{\mid}^{p-2}u\\{\hfill{10}}={\ell}k^{-1}F_u(x,\;u,\;v)+{\lambda}{\alpha}(x){\mid}u{\mid}^{m-2}u,\;x{\in}{\Omega}\\M_2([u]^q_{s,q})(-{\Delta})^s_qv+V_2(x){\mid}v{\mid}^{q-2}v\\{\hfill{10}}={\ell}k^{-1}F_v(x,u,v)+{\mu}{\alpha}(x){\mid}v{\mid}^{m-2}v,\;x{\in}{\Omega},\\u=v=0,\;x{\in}{\partial}{\Omega},$$ where ${\Omega}{\subset}{\mathbb{R}}^N$ is an unbounded domain with smooth boundary ${\partial}{\Omega}$, and $0<s<1<p{\leq}q$ and sq < N, ${\lambda},{\mu}>0$, $1<m{\leq}k<p^*_s$, ${\ell}{\in}R$, while $[u]^t_{s,t}$ denotes the Gagliardo semi-norm given in (1.2) below. $V_1(x)$, $V_2(x)$, $a(x):{\mathbb{R}}^N{\rightarrow}(0,\;{\infty})$ are three positive weights, $M_1$, $M_2$ are continuous and positive functions in ${\mathbb{R}}^+$. Using variational methods, we prove existence of infinitely many high-energy solutions for the above system.

Characterization and utilization of a cytoplasmic male sterility line of Wucai (Brassica campestris L.)

Guohu Chen,Xinyu Ye,Fanli Zeng,Jian Wang,Lingyun Yuan,Shidong Zhu,Jinfeng Hou,Yuan Cheng,Chenggang Wang 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.3

The novel male sterility line 12-14A of Wucai ( Brassica campestris ) was generated by backcrossing. In this study, morphological,molecular, and cytological analyses were performed to characterize this line. The phenotypes of fl ower organsof 12-14A were diff erent from those of its maintainer line 12-14B, as the fl owers of 12-14A were completely infertile. Molecular analysis confi rmed that the male sterility line 12-14A was classifi ed as the ogu CMS type. An analysis of antherdevelopment in the CMS line demonstrated that two types of abortion occur simultaneously: pollen mother cell abortionand tetrad-to-mononuclear microspore abortion. In addition, the mature anthers of 12-14A showed typical abortive features,such as appearing dry, shrunken, and scaly. A heterosis test of hybrids from CMS 12-14A and four inbred lines was carriedout, and the F 1 hybrids exhibited clear heterosis in plant weight, as well as in the protein, soluble sugar, and vitamin C content,suggesting high yields and high quality potential. These results indicate that this novel CMS line may have powerfulpotential in Wucai hybrid breeding.

Distribution Rules of Nutrients in Orobanche Aegyptiaca-Tomato Parasitic System

Jinhu Zhi,Jinfeng Chen,Qiangqing Zheng,Shuzhen Zhao,Desheng Wang 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.3

The research put forward the concept of parasitic system for the first time and studied distribution rules of N, P and K nutrients of different soil areas and different plant tissues in the system along with changes in the tomato growth period, as well as relevance between rhizosphere soil and nutrient contents in different plant tissues. It is found in the results that when Orobanche aegyptiaca was parasitized in tomatoes and joined nutrient transmission via a certain channel, the nutrients in tomato rhizosphere soil would firstly be transported into aboveground parts and Orobanche aegyptiaca by its transfusion tissue; content changes of rapidly-available N, P and K in Orobanche aegyptiaca rhizosphere soil, tomato rhizosphere soil and non-rhizosphere soil showed certain high-low complementarity; content changing trends of N, P and K in different organs of tomatoes and Orobanche aegyptiaca had certain relations, but would differ along with variation of tomato growth period; contents of rapidly-available N and K in Orobanche aegyptiaca rhizosphere soil showed significant correlation with total contents of N and K in organs of tomato and Orobanche aegyptiaca.

Enhanced activity and hydrothermal stability of Rh-based three-way catalyst for emission control from motorcycles with the assistance of monoethanolamine

Li Lan,Jinfeng Wang,Shanhu Chen,Dacheng Li,Hongmei Li,Dayu Liu,Wei Wang,Yaoqiang Chen 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.71 No.-

In this work, an advanced Rh/CeO2–ZrO2 (Rh/CZ) three-way catalyst was synthesized with the assistanceof monoethanolamine. Compared with conventional Rh/CZ, the dispersion and oxidation state of Rhspecies, as well as the hydrothermal aging resistance are remarkably modified. That is, upon agingtreatment, conventional Rh/CZ undergoes severe agglomeration of Rh species and formation of largeamount of reduction-resistive RhO2, resulting in serious catalyst deactivation. Fortunately, after theintroduction of monoethanolamine, the sintering of Rh species and transformation into inactive RhO2upon aging are effectively suppressed. Consequently, improved reducibility and advanced three-waycatalytic activity are achieved for the modified catalyst.