Experimental and Numerical Investigation of the Tensile Performance and Failure Process of a Modified Portland Cement

Jianhang Chen,Kangming Tao,Banquan Zeng,Lei Liu,Hongbao Zhao,Junwen Zhang,Danqi Li 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.1

A better understanding of the tensile performance and tensile failure mechanism of cement paste is significant in preventing rock reinforcement failure. Therefore, this paper aims to reveal the tensile performance and failure mechanism of a modified Portland cement: Stratabinder HS cement. To achieve this objective, the split tensile test was conducted on specimens followed by simulating the failure mechanism numerically. The results indicated that the water–cement rate significantly influenced the tensile performance of the cement paste. When the water–cement rate increased from 0.35 to 0.42, the tensile strength declined from 1.9 MPa to 1.5 MPa. It was also observed that vertical tensile failure constantly occurred regardless of the water–cement rate. During the testing process, tensile cracks and shear cracks occurred. The increasing rate in the number of specimen cracks was dependent on the tensile stress state. Before the tensile stress reached the peak, the crack quantity increased slightly. After the peak, the crack quantity increased dramatically. During the vertical loading process, horizontal tensile stress occurred in the specimen. This horizontal tensile stress zone showed a diamond shape. The higher the tensile stress is, the larger the area of the horizontal tensile stress zone. When the tensile strength was reached, horizontal tensile stress mainly concentrated at the vertical centre of the specimen. This finally led to tensile failure of the specimen. This paper indicated that the water–cement rate was the key factor in evaluating the tensile strength of the Stratabinder HS cement.

Parameter design of active damping‑based shunt hybrid active power filters

Jianhang Lu,Miao Zhang,Junming Wen,Dali Zheng,Shaoli Deng,Xiang Shi,Ling Yang 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.5

This paper presents the parameter design of a new topology of hybrid active power filter (HAPF), which makes the system capacity smaller. Based on the main topological circuit, the passive LC single-tuned circuit shunted into the HAPF effectively reduces the capacity of the system. By introducing the grid voltage feedforward method, the DC-side voltage control becomes relatively stable, and the fundamental reactive current flowing through the converter is effectively reduced. Meanwhile, to suppress the resonance of the HAPF, the state variable feedback method is adopted. According to theoretical analysis, a simulation model of the system is built in the MATLAB environment. Then a low-voltage experimental HAPF platform is built to validate the result of the simulations.

Partition Improvement of Cephalexin and 7-aminodeacetoxicephalospronic Acid in Aqueous Two-phase Systems for Cephalexin Synthesis

Xuejun, Cao,Jianhang, Zhu,Dongzhi, Wei,Hur, Byong Ki 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.3

Partition behavior of cephalexin and 7-ADCA in PEG-salts and EOPO-salts aqueous two-phase systems has been investigated under various different conditions. Effect of polymer molecular weight, salts types, tie line length on partition coefficients of cephalexin and 7-ADCA were described. Additives such as salts, water miscible solvents and surfactants were used to improve partition of cephalexin and 7-ADCA. NaSCN shows greatest influence on partition of cephalexin and 7-ADCA in 20% PEG 400-17.5% (NH_4)_2SO_4. Cephalexin and 7-ADCA partition coefficients reached 12.92 and 2.58, respectively. While NaCI shows greatest influence on partition of cephalexin and 7-ADCA in E0_40PO_60-(NH_4)_2SO_4. In 15% E0_40P0_60-13% (NH_4)_2SO_4 ATPS, partition coefficients of cephalexin and 7-ADCA reached 0.08 and 0.42, respectively. Cephalexin and 7-ADCA shows different partition trend in PEG-(NH_4)_2SO_4 and EOPO-(NH_4)_2SO_4 ATPS. In EOPO-(NH_4)_2SO_4 ATPS, diagrams of PEG3000-(NH_4)_2SO_4, E0_40PO_60-(NH_4)_2SO_4, E0_20PO_80-(NH_4)_2SO_4 were prepared and their differences were analyzed, and recovery of E0_40PO_60-(NH_4)_2SO_4 ATPS was performed with yield of 90-95%.

Application of advanced biomaterials in photothermal therapy for malignant bone tumors

Bo Chao,Jianhang Jiao,Lili Yang,Yang Wang,Weibo Jiang,Tong Yu,Linfeng Wang,He Liu,Han Zhang,Zhonghan Wang,Minfei Wu 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Malignant bone tumors are characterized by severe disability rate, mortality rate, and heavy recurrence rate owing to the complex pathogenesis and insidious disease progression, which seriously affect the terminal quality of patients' lives. Photothermal therapy (PTT) has emerged as an attractive adjunctive treatment offering prominent hyperthermal therapeutic effects to enhance the effectiveness of surgical treatment and avoid recurrence. Simultaneously, various advanced biomaterials with photothermal capacity are currently created to address malignant bone tumors, performing distinctive biological functions, including nanomaterials, bioceramics (BC), polymers, and hydrogels et al. Furthermore, PTT-related combination therapeutic strategies can provide more significant curative benefits by reducing drug toxicity, improving tumor-killing efficiency, stimulating anti-cancer immunity, and improving immune sensitivity relative to monotherapy, even in complex tumor microenvironments (TME). This review summarizes the current advanced biomaterials applicable in PTT and relevant combination therapies on malignant bone tumors for the first time. The multiple choices of advanced biomaterials, treatment methods, and new prospects for future research in treating malignant bone tumors with PTT are generalized to provide guidance.

Partition Improvement of Cephalexin and 7-aminodeacetoxicephalospronic Acid in Aqueous Two-phase Systems for Cephalexin Synthesis

Byung Ki Hur,Zhu Jianhang,Wei Dongzhi,Cao Xuejun 한국공업화학회 2002 Journal of Industrial and Engineering Chemistry Vol.8 No.3

A Novel Control Strategy for Improving the Performance of Hybrid Active Power Filters

Wen Junming,Zhang Miao,Lu Jianhang,Guan YiChuan,Wu Shiyu,Feng Chunshou 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6

Hybrid active power filters (HAPF) are effective harmonic compensation devices. However, the inductor voltage is too low, so the DC-bus voltage can not get enough power flow. Thus, the compensation performance and stability of HAPF can be reduced. Theoretically, increasing the inductor voltage can improve the DC side control performance. Therefore, the relevant mathematical model is established, and systematic analysis is carried out. To improve the performance of HAPF, a new double closed-loop control strategy is proposed. To sum up, the main variable of the outer loop control is the inductor voltage. The current flow direction can be changed by changing the value of the inductance voltage to improve the inductance voltage and realize the stability of the DC-side voltage. Secondly, from the transfer function and the Bode Plots, the introduction of the inverter output current inner loop results in significant resonant spike suppression of the system. Compared with the self-excitation control method with voltage feedforward, this new control method is easy to implement and very effective in DC-bus control. Simulation and experimental results show that the compensation effect of HAPF is improved, the DC-side voltage is stable, and the system can operate safely and reliably.

Learning Curve and Complications of Unilateral Biportal Endoscopy: Cumulative Sum and Risk-Adjusted Cumulative Sum Analysis

Jinchao Xu,Dong Wang,Jidan Liu,Chengyue Zhu,Jianhang Bao,Wenshuo Gao,Wei Zhang,Hao Pan 대한척추신경외과학회 2022 Neurospine Vol.19 No.3

Objective: The purpose of this study was to investigate the learning curve and complications of unilateral biportal endoscopy (UBE) in the treatment of lumbar disc herniation (LDH) and lumbar spinal stenosis (LSS). Methods: This was a retrospective cohort analysis of 197 consecutive patients who received UBE unilateral laminotomy bilateral decompression (UBE-ULBD) or lumbar discectomy (UBE-LD) surgery, including 107 males and 90 females with an average age of 64.83 ± 14.29 years. Cumulative sum (CUSUM) and risk-adjusted cumulative sum analysis (RA-CUSUM) were used to evaluate the learning curve, with the occurrence of complications defined as surgical failure, and variables of different phase of the learning curve were compared. Results: The cutoff point of learning curve of UBE surgery was 54 cases according to CUSUM analysis. The learning curve of UBE-ULBD and UBE-LD were divided into 3 phases. The first cutoff points were 31 and 12 cases, and the second cutoff point were 67 and 32 cases respectively. With the progress of the learning curve, the operation time and postoperative hospital stays decreased. The visual analogue scale and Oswestry Disability Index at the last follow-up were significantly lower than that before surgery. The incidence of surgical failure was 6.11% and began to decrease after the 89th case based on RA-CUSUM analysis. The surgical failure rate decreased from 10.11% to 2.78 after the 89th case with significant different. Conclusion: UBE surgery is effective in the treatment of LDH and LSS with low incidence of complications. But a learning curve of at least 54 cases still required for mastering UBE surgery.