Analysis and research on dynamic characteristics of 3D braided composite two-stage reducer case

Weiliang Zhang,Xupeng Wang,Xiaomin Ji,Xinyao Tang,Fengfeng Liu,Shuwei Liu,Mingjun Liu,Xiao-Long Gao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.6

Based on the analysis of the movement rule of 3D five-way braided yarn, the 3D five-way braided case model is divided into three parts: base, case bottom plate and case wall. According to the characteristics of each part, the braiding and forming principle of a 3D five-way composite case was analyzed. Under the assumption of ignoring the influence of friction, bearing and other factors on the system, the differential equations of motion of the two-stage gear transmission system with case were established. The two-stage gear transmission system was numerically analyzed by Euler method, and the influence of dimensionless meshing frequency, clearance, case mass and damping on the dynamic characteristics of the transmission system was studied. After that, high and low frequency disturbance was applied to the input case. The research shows that the damping ratio of the composite case increases and the low frequency attenuation is accelerated due to the decrease of the case mass, so the composite case has better shock resistance to low frequency interference.

Simulation of Grid-Connected Solar Micro-inverter Based on Fuzzy PI Controller

Weiliang Liu,Changliang Liu,Huichao Zhang,Yongjun Lin,Liangyu Ma 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.10

Grid-connected solar micro-inverter is a highly nonlinear and time-varying system, so it is difficult to achieve good control effect using traditional PI controller. In this paper, small signal analysis model of micro-inverter is established, grid-connected current control strategy composed of fuzzy PI controller and grid voltage feed-forward is put forward, and the initial parameters of PI controller is optimized using the genetic algorithm. Simulation results show that the control strategy has the virtues of good robustness, small dynamic deviation, and could reduce the harmonic content of grid-connected current.

Optimal strategy for energy management of DC multi‑microgrids considering power loss

Weiliang Zhang,Hui Zhang,Na Zhi,Hanwei Wang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.4

DC multi-microgrids (DC MMG) improve power supply efficiency. However, they also increase transmission power loss. To reduce the power loss of the DC MMG, an optimization strategy of energy management with an adaptive distribution coefficient is proposed in this paper. By adjusting the power distribution coefficient of each DC microgrid (DC MG), the power distribution of the DC MMG is optimized to reduce power loss. In addition, to quickly predict changes of the DC MG power, the traditional finite control set model predictive control (FCS-MPC) is improved. The duty cycle of the converter is directly calculated according to the change of the current. Finally, experimental verification and comparison show that the proposed method can minimize the power loss of a DC MMG and speed up the balance of power.

Short-duration chemoprophylaxis might reduce incidence of deep vein thrombosis in Asian patients undergoing total knee arthroplasty

Zhang Siyuan,Htet Kway Swar,Tan Xin Yang,Wang Xinyu,Wang Wilson,Chua Weiliang 대한슬관절학회 2020 대한슬관절학회지 Vol.32 No.-

Venous thromboembolism (VTE) is a serious complication that may occur after total knee arthroplasty (TKA), leading to the recommendation of routine chemoprophylaxis by international guidelines. This study aims to determine if short-duration chemoprophylaxis after TKA reduces the incidence of VTE in an Asian population.A retrospective study of 316 patients who underwent unilateral primary TKA between 1 January 2011 and 31 December 2013 was conducted. All patients received mechanical prophylaxis. One hundred seventeen patients (37%) received additional chemoprophylaxis, whereas 199 patients (63%) did not. A Doppler ultrasound (DUS) of both lower limbs was conducted for all patients within 6 days after surgery (median = 3 days) to assess for both proximal and distal DVT. Chemoprophylaxis in the form of enoxaparin (low molecular weight heparin; LMWH), aspirin, or heparin was administered until patients had a normal DUS, for a median duration of 4 days. Patients were followed up clinically for a minimum of 6 months to monitor for delayed or recurrent VTE and at least 2 years for patient-reported outcome measures. Overall, 24 patients (7.59%) developed deep vein thrombosis (DVT): three proximal and 21 distal DVTs. Twenty-three of the 24 patients were asymptomatic. Twenty of 199 patients (10.05%) with only mechanical prophylaxis developed DVT, whereas four of 117 patients (3.42%) with additional chemoprophylaxis developed DVT. Multivariate analysis showed that chemoprophylaxis use was associated with reduced incidence of DVT (odds ratio = 0.19, p value = 0.011). Other factors associated with increased DVT incidence include female gender (odds ratio = 5.45, p value = 0.034), positive history of cancer (odds ratio = 5.14, p value = 0.044), and increased length of stay in hospital (odds ratio = 1.19, p value < 0.001). Our study has shown that despite the low incidence of DVT in Asian patients undergoing TKA, short-duration chemoprophylaxis might be effective in reducing the incidence of DVT. However, most DVTs observed in our study were distal and may be of limited clinical significance. Further studies are needed to investigate the impact of chemoprophylaxis use on the incidence of PE and overall mortality rates among Asian patients.

Catalytic performance of amino acid/phosphotungstic acid as bi-functional heterogeneous catalyst for biodiesel production

Qingyu Zhang,Xiaoling Duan,Siyi Tang,Cunwen Wang,Weiguo Wang,Weiliang Feng,Tielin Wang 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.1

In this study, a series of acid-base bi-functional catalysts were prepared by mixing different amounts of basic amino acids (AAs) and phosphotungstic acid (PTA), which exhibited the excellent performance in catalyzing conversion of oleic acid (OA) for the biodiesel production. The physicochemical properties of the catalysts were characterized and analyzed using modern testing techniques and characterization methods such as XRD, FT-IR, XPS, SEM, TEM, and Hammett titration. The various influence parameters were optimized using the central composite design based the response surface methodology, where the maximum biodiesel yield of 97.0% was achieved at the MeOH/OA molar ratio of 5.9, the catalyst loading of 8%, reaction time of 6 h, and reaction temperature of 65℃. Furthermore, the stability and reusability of the prepared catalyst were also demonstrated. At last, the possible catalytic mechanism of the prepared catalyst was comprehensively described.

Effect of Salts on the Thermal Stability of Physically Crosslinked Gelatin Hydrogels

Jianlong Zhang,Congde Qiao,Xianguang Ma,Weiliang Liu,Qinze Liu 한국고분자학회 2017 폴리머 Vol.41 No.4

The effects of preparation conditions, such as polymer concentration, annealing temperature, annealing time and pH, on the melting behavior of gelatin gels were investigated. An optimum condition of gel preparation for calorimetric test is obtained. In addition, the influence of salt including salt concentration and salt type on the melting behavior of gelatin gels was explored by DSC and rheometer. It was found that the melting temperature first increased and then decreased with an increase in salt concentration. This result indicates that electrostatic interactions are important for the formation and stability of gelatin gels. Moreover, the melting temperature of polymer gels with different salt addition conforms to the following orders: Na<SUP>+</SUP><Ca<SUP>2+</SUP><Cr<SUP>3+</SUP>. The different trend observed in respect of the storage modulus indicated that the triple helices dominated the gelatin gel strength, and the binding mechanism of Ca2+ may be different from that of Cr<SUP>3+</SUP>.

Spatio-temporal expression pattern and fasting response of follistatin gene in teleost Larimichthys crocea

Zhifei Liu,Liangyi Xue,Weiliang Shen,Jun Ying,Zhenhua Zhang 한국유전학회 2014 Genes & Genomics Vol.36 No.2

Follistatin is a multifunctional regulatory proteininvolved in numerous physiological activities. Tobetter understand its functions in Larimichthys crocea (L.crocea), the entire cDNA sequence of follistatin from L. crocea was cloned, the transcript abundance of follistatinwas measured at different development stages and in differentgender. A fasting-refeeding protocol was also performedto correlate follistatin tissue expression withnutritional status in the juvenile stage of L. crocea. Theresults showed that follistatin transcripts were weaklydetected before gastrula stage (9 h post-fertilization; hpf),and at the highest level at myogenesis stage (15 hpf) and 30days after hatching (30 dah). In adult fish, follistatin transcriptswere observed in all the ten tissues examined andmost abundant in eye, gill, muscle, brain and intestine. Moreover, the abundance of follistatin transcripts in mosttissues was influenced by the age and gender. Duringfasting and refeeding period, the regulatory response offollistatin in muscle, liver, gonad, spleen and brain of L. crocea varied greatly. Altogether, these findings supportthe evidence that follistatin plays a profound role in theteleost development and that it is an indispensable factorfor the survival of teleosts when challenged with environmentalstresses like fasting.

Performance and Mechanism Analysis of Succinate Production under Different Transporters in Escherichia coli

Xiaozhan Li,Wenming Zhang,Mingke Wu,Fengxue Xin,Weiliang Dong,Hao Wu,Min Zhang,Jiangfeng Ma,Min Jiang 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.5

Succinic acid is a platform chemical with potential for bio-based synthesis. However, the production of bio-based succinate is limited because of insufficient succinate efflux capacity in the late stage of fermentation. In the present study, three different transporters, which have been reported to be responsible for C4-dicarboxylates transport, were employed for investigation of the transport capacity of succinate in Escherichia coli. After engineered strains were constructed, the fermentative production of succinic acid was studied in serum bottles and 3 L of fermentor. The results demonstrated that engineered strain showed better efflux capacity than control strain under high concentration of succinate. The highest production of succinate was 68.66 g/L, while the NCgl2130 transporter may be the best candidate for succinate export in E. coli. Further research showed that the expression levels and relative enzyme activities involved in the metabolic pathway all increased markedly, and the maximum activities of PPC, PCK, PYK, and MDH increased by 1.50, 1.38, 1.28, and 1.27-fold in recombinant E. coli AFP111/pTrc99a- NCgl2130, respectively. Moreover, the maximum level of intracellular ATP increased by 23.79% in E. coli AFP111/ pTrc99a-NCgl2130. Taken together, these findings indicated that engineered transporters can improve succinate production by increasing key enzyme activities and intracellular ATP levels. To the best of thew authors’ knowledge, this is the first report on a mechanism to improve succinate production by engineered transporters. This strategy set up a foundation for improving the biosynthesis of other C4-dicarboxylates, such as fumaric acid and malic acid.

Calculation of Deflection and Stress of Assembled Concrete Composite Beams under Shrinkage and Creep and Its Application in Member Design Optimization

Yan Fang,Jianghong Mao,Yixue Zhang,Weiliang Jin,Diwei Tang,Jun Zhang 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.9

There are a large number of concrete bonding interfaces in assembled concrete structures. Moreover, the problems of deformation and coordination at the interfaces lead to weak bonding under shrinkage and creep. The theoretical methods and analytical solutions for the long-term performance of composite structures in recent literatures are relatively complicated for the review or optimization in the design stage. Hence, a method for calculating the mid-span deflection of and the cross-sectional stress on composite beams under shrinkage and creep was developed based on the average curvature method. The calculation method was then verified by the experiments and the numerical simulations. Further, factors affecting the deflection of and the stress on the assembled concrete composite beams, including the loading age, the reinforcement ratio, the section dimensions, and the surface area in contact with the atmosphere were analyzed by using the developed method. The results revealed that the adjustment of the section dimensions and the loading time is the effective optimization approach. A framework for review or optimization of composite concrete beams based on the sensitivity analysis is proposed and a case study is carried out. The results of this work can helpfully be used to control the risk of additional deflections or cracking during the long-term operation of buildings.

Extraction of bioethanol from fermented sweet sorghum bagasse by batch distillation

Guangming Li,Jihong Li,Shizhong Li,Xu Zu,Lei Zhang,Lisong Qi,Weiliang Xu 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.1

Extraction of bioethanol, a potential alternative to fossil fuel in the transport industry, from sweet sorghum stems [Sorghum bicolor (L.) Moench] using solid-state fermentation (SSF) technology has become a popular research topic worldwide. Because SSF technology can directly convert fermentable sugars into target products without juice squeezing and water input, this method can potentially reduce energy and water consumption. However, ethanol extraction from fermented sweet sorghum bagasse requires further investigation. We used batch solid-state distillation to investigate the optimal operating parameters in a distillation column (diameter, 400 mm) via a single-factor experiment. Results showed that the optimal steam flow rate and loading height were 8-10 kg·h−1 and 700-1,000 mm, respectively. Under optimal conditions, an energy consumption of 3.82 tons of steam per ton of ethanol and distillate concentration of 60.9% (v/v) were obtained. The pseudo-first-order rate equation was used to describe the distillation kinetics, and good correlations were obtained. Therefore, solid-state distillation can be effectively used to extract ethanol from fermented sweet sorghum bagasse.