Numerical analysis on stability of express railway tunnel portal

Xiaojun Zhou,Hongyun Hu,Bo Jiang,Yuefeng Zhou,Yong Zhu 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.1

On the basis of the geological conditions of high and steep mountainous slope on which an exit portal of an express railway tunnel with a bridge-tunnel combination is to be built, the composite structure of the exit portal with a bridge abutment of the bridge-tunnel combination is presented and the stability of the slope on which the express railway portal is to be built is analyzed using three dimensional (3D) numerical simulation in the paper. Comparison of the practicability for the reinforcement of slope with in-situ bored piles and diaphragm walls are performed so as to enhance the stability of the high and steep slope. The safety factor of the slope due to rockmass excavation both inside the exit portal and beneath the bridge abutment of the bridge-tunnel combination has been also derived using strength reduction technique. The obtained results show that post tunnel portal is a preferred structure to fit high and steep slope, and the surrounding rock around the exit portal of the tunnel on the high and steep mountainous slope remains stable when rockmass is excavated both from the inside of the exit portal and underneath the bridge abutment after the slope is reinforced with both bored piles and diaphragm walls. The stability of the high and steep slope is principally dominated by the shear stress state of the rockmass at the toe of the slope; the procedure of excavating rockmass in the foundation pit of the bridge abutment does not obviously affect the slope stability. In-situ bored piles are more effective in controlling the deformation of the abutment foundation pit in comparison with diaphragm walls and are used as a preferred retaining structure to uphold the stability of slope in respect of the lesser time, easier procedure and lower cost in the construction of the exit portal with bridge-tunnel combination on the high and steep mountainous slope. The results obtained from the numerical analysis in the paper can be used to guide the structural design and construction of express railway tunnel portal with bridge-tunnel combination on high and abrupt mountainous slope under similar situations.

Removal of Chromium (Ⅵ) by Escherichia coli Cells Expressing Cytoplasmic or Surface-Displayed ChrB: a Comparative Study

( Xiaofeng Zhou ),( Jianghui Li ),( Weilong Wang ),( Fan Yang ),( Bingqian Fan ),( Chenlu Zhang ),( Xiaojun Ren ),( Feng Liang ),( Rong Cheng ),( Fengying Jiang ),( Huaibin Zhou ),( Juanjuan Yang ),( 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.7

Various genetically engineered microorganisms have been developed for the removal of heavy metal contaminants. Metal biosorption by whole-cell biosorbents can be enhanced by overproduction of metal-binding proteins/peptides in the cytoplasm or on the cell surface. However, few studies have compared the biosorption capacity of whole cells expressing intracellular or surface-displayed metal-adsorbing proteins. In this study, several constructs were prepared for expressing intracellular and surface-displayed Ochrobactrum tritici 5bvl1 ChrB in Escherichia coli BL21(DE3) cells. E. coli cells expressing surface-displayed ChrB removed more Cr(VI) from aqueous solutions than cells with cytoplasmic ChrB under the same conditions. However, intracellular ChrB was less susceptible to variation in extracellular conditions (pH and ionic strength), and more effectively removed Cr(VI) from industrial wastewater than the surface-displayed ChrB at low pH (<3). An adsorptiondesorption experiment demonstrated that compared with intracellular accumulation, cell-surface adsorption is reversible, which allows easy desorption of the adsorbed metal ions and regeneration of the bioadsorbent. In addition, an intrinsic ChrB protein fluorescence assay suggested that pH and salinity may influence the Cr(VI) adsorption capacity of ChrB-expressing E. coli cells by modulating the ChrB protein conformation. Although the characteristics of ChrB may not be universal for all metal-binding proteins, our study provides new insights into different engineering strategies for whole-cell biosorbents for removing heavy metals from industrial effluents.

A Low Power Consumption Frequency Adaptation Mechanism Based on the Traffic and Implementation on NetFPGA

Lei Zhou,Lianghua Li,Xiaoju Liu,Xiaojun Wang 보안공학연구지원센터 2014 International Journal of Future Generation Communi Vol.7 No.6

Both in academic and industrial research, building a green energy-saving network has become a hot topic. Combined with hardware division and adaptive algorithm, this paper proposes an adaptive frequency control mechanism based on traffic to reduce power consumption. By calculating real-time traffic, the network device can adjust its operating frequency. On the premise of maintaining network performance, this mechanism could reduce the power consumption significantly. Besides, the adaptive frequency mechanism has been verified and realized in the NetFPGA Reference Router. Experimental data show that under different ranges of traffic loads and without affect its performance, the Router embedded this mechanism can reduce power consumption by more than 20%.

Development of a simple nomogram to estimate risk for intraoperative complications before partial nephrectomy based on the Mayo Adhesive Probability score combined with the RENAL nephrometry score

Xiaojun Tan,Dachun Jin,Jian Hu,Weili Zhang,Yu Zhou,Yunxiang Li,Yuanfeng Zhang,Ji Wu 대한비뇨의학회 2021 Investigative and Clinical Urology Vol.62 No.4

Purpose: This study aimed to develop a simple nomogram based on the Mayo Adhesive Probability (MAP) score combined with the RENAL nephrometry score (RNS) to predict intraoperative complications before partial nephrectomy (PN) in Asian populations. Materials and Methods: This study retrospectively collected patients undergoing PN at three medical centers. Each component of the MAP score and the RNS (6 variables) was evaluated to assess its association with intraoperative complications by multivariable logistic regression with backward elimination. Results: A total of 46 cases (7.2%) with intraoperative complications were identified among 637 patients. After backward elimination, three variables, including tumor diameter (4–7 cm vs. ≤4 cm: odds ratio [OR], 4.339; 95% confidence interval [CI], 1.943–9,692; ≥7 cm vs. ≤4 cm: OR, 8.434; 95% CI, 1.225–58.090), nearness to the collecting system (4–7 mm vs. ≥7 mm: OR, 2.988; 95% CI, 1.293–6.907; ≤4 mm vs. ≥7 mm: OR, 21.394; 95% CI, 6.122–74.756), and perirenal fat stranding type (type 1 vs. no stranding: OR, 3.119; 95% CI, 1.079–9.017; type 2 vs. no stranding: OR, 18.722; 95% CI, 6.757–51.868), were retained. The predictive power (measured by area under the curve [AUC]) of the nomogram was observed to be superior to the RNS or MAP score alone (RNS: 0.686, MAP score: 0.729, the nomogram: 0.837), but comparable to their combination (0.813). Conclusions: The simple nomogram contains fewer components than the combination of the RNS and MAP scores yet demonstrates equivalent predictive power for intraoperative complications.

Microstructure and Magnetic Properties of Plasma-Sprayed Fe<SUB>73.5</SUB>Cu1Nb₃Si<SUB>13.5</SUB>B₉ Coatings

Xiaojun Ni,Xihui Bo,Jiawei Wu,Jinhua Guo,Zhichao Lu,Shaoxiong Zhou 한국자기학회 2010 한국자기학회 학술연구발표회 논문개요집 Vol.2010 No.12

Numerical investigation on seismic performance of reinforced rib-double steel plate concrete combination shear wall

Zhou Longyun,Li Xiaohu,Li Xiaojun 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.1

Double steel plate concrete composite shear wall (SCSW) has been widely utilized in nuclear power plants and high-rise structures, and its shear connectors have a substantial impact on the seismic performance of SCSW. Therefore, in this study, the mechanical properties of SCSW with angle stiffening ribs as shear connections were parametrically examined for the reactor containment structure of nuclear power plants. The axial compression ratio of the SCSW, the spacing of the angle stiffening rib arrangement and the thickness of the angle stiffening rib steel plate were selected as the study parameters. Four finite element models were constructed by using the finite element program named ABAQUS to verify the experimental results of our team, and 13 finite element models were established to investigate the selected three parameters. Thus, the shear capacity, deformation capacity, ductility and energy dissipation capacity of SCSW were determined. The research results show that: compared with studs, using stiffened ribs as shear connectors can significantly enhance the mechanical properties of SCSW; When the axial compression ratio is 0.3–0.4, the seismic performance of SCSW can be maximized; with the lowering of stiffener gap, the shear bearing capacity is greatly enhanced, and when the gap is lowered to a specific distance, the shear bearing capacity has no major affect; in addition, increasing the thickness of stiffeners can significantly increase the shear capacity, ductility and energy dissipation capacity of SCSW. With the rise in the thickness of angle stiffening ribs, the improvement rate of each mechanical property index slows down. Finally, the shear bearing capacity calculation formula of SCSW with angle stiffening ribs as shear connectors is derived. The average error between the theoretical calculation formula and the finite element calculation results is 8% demonstrating that the theoretical formula is reliable. This study can provide reference for the design of SCSW.

Active current-limiting control to handle DC line fault of overhead DC grid

MENG Zhou,WANG Xiang,WENPING Zuo,WEIXING Lin,JINYU Wen,RUIZHANG Yang,BINYE Ni,XIAOJUN Lu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

To handle with the DC line faults in a DC grid, this paper proposed an active current-limiting controller for hybrid MMC. With this active current-limiting control strategy, the requirement of interruption current of DCCB will be significantly decreased, and the investment of DC grid will be reduced obviously. Firstly, the control architecture of active current-limiting controller is disclosed. To avoid the overvoltage of submodule capacitors during DC fault, a dynamic limiter for the reference value of the DC current controller is proposed. To decrease the peak of fault current, the feedforward controller of DC voltage is put forward. The decoupling controllability of the AC/DC voltage of hybrid MMC is disclosed. The currentlimiting mechanism of the active current-limiting controller is analysis. Then, the validity of the active current-limiting control strategy is verified by RTDS.

Characteristics of progestin- insensitive early stage endometrial cancer and atypical hyperplasia patients receiving second-line fertility-sparing treatment

Shuang Zhou,Zhiying Xu,Bingyi Yang,Jun Guan,Weiwei Shan,Yue Shi,Xiaojun Chen 대한부인종양학회 2021 Journal of Gynecologic Oncology Vol.32 No.4

Objective: This study investigated the characteristics of progestin-insensitive endometrioid endometrial cancer (EEC) and atypical endometrial hyperplasia (AEH) patients receiving fertility-sparing treatments and assessed the therapeutic effects of second-line fertility- preserving treatments. Methods: Three hundred and thirty-eight patients with EEC (n=75) or AEH (n=263) receiving fertility-preserving treatment were retrospectively analyzed. ‘Progestin-insensitive’ was defined as meeting one of the following criteria: 1) presented with progressed disease at any time during conservative treatment, 2) remained with stable disease after 7 months of treatment, and/or 3) did not achieve complete response (CR) after 10 months of treatment. Clinical characteristics and treatment results of progestin-insensitive patients receiving second-line treatment and those of progestin-sensitive patients were compared. Results: Eight-two patients (59 AEH and 23 EEC) were defined as progestin-insensitive and 256 as progestin-sensitive. In multivariate analysis, body mass index ≥28.0 kg/m2 (odds ratio [OR]=1.898) and lesion size >2 cm (OR=2.077) were independent predictors of progestin- insensitive status. Compared to AEH patients, progestin-insensitive EEC patients had poorer second-line treatment responses (28-week cumulative CR rate after changing second-line treatment, 56.3% vs. 85.4%, p=0.011). No statistical difference was found in CR rate among different second-line treatments. Conclusion: Obesity and larger lesion size were independent risk factors associatedwith progestin-insensitive status. In progestin-insensitive patients receiving second-line treatment, EEC patients had lower CR rate comparing with AEH patients. Further study with larger sample size is needed to evaluate efficacy of different second-line treatments for progestin insensitive patients.

Generalized-extended-state-observer-based Sliding-mode Control for Buck Converter Systems

Lan Zhou,Xiaojun Yi,Zhuang Jiang,Zhu Zhang,Jinhua She 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.12

This paper presents a generalized-extended-state-observer (GESO)-based sliding-mode control (SMC) method to deal with mismatched parameter uncertainty and reference-input mutation for a class of DC-DC buck converter systems (BCS). First, a GESO is designed to estimate the total disturbance together with the system state. Then, by choosing an appropriate disturbance-compensation gain, a composite SMC law is designed to attenuate the influence of the parameter uncertainty and reference input mutation on the system output. Both the stability criterion and deign procedure of the system are given. Finally, simulation results show that the designed GESO-based SMC system for the DC-DC BCS is robustly stable and achieves both satisfactory transient and steady-state performance. Comparisons demonstrate that the proposed method provides better transient and steady-state performance for both disturbance rejection and tracking control than either conventional SMC or ESO-based control approach does.

Predicting the Fracture Characteristics of Concrete Using Ensemble and Meta-heuristic Algorithms

Quan Zhang,Xiaojun Zhou 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

Fracture properties are crucial for the design and application of concrete materials. Thefracture energy which represents the fracture performance of concrete always suffers theinfluence of various factors, making it difficult to accurately predict the fracture energy ofconcrete with traditional methods. Thus, the artificial intelligence (AI) approaches areemployed to establish the predictive models for the concrete fracture energy. Additionally, thefirefly meta-heuristic algorithm (FA) is used to search for the optimum model hyper-parameters. The FA algorithm is proved to be efficient in tuning the hyper-parameters of the three models,and optimum values are obtained within ten iterations. Compared with the single classification andregression tree algorithm (CART), the ensemble algorithm appears to be more accurate andgeneralizable. Moreover, through the importance evaluation of different features in theoptimum predictive model, the aggregate characteristics (aggregate size distribution andmaximal aggregate size) and specimen size have been proven to be dominant factors for thepredictive models, which should be carefully considered in predictive work regardingconcrete fracture properties.