Vibration and noise source identification methods for a diesel engine

Jiaxin Xi,Zengming Feng,Guoqiang Wang,Fei Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1

In this study, we used a four-cylinder inline diesel engine as an example to explain how to use test methods and multi-body dynamictechniques to identify the exact source of noise and vibration. A 1 meter noise test was conducted to indicate that the engine front end isthe main source of noise. The near-field sound intensity method and the near-field acoustic holography technique were used to identifythe chain drive system as the source of noise and vibration. A 3D dynamic analysis model of the timing chain drive system was establishedusing RecurDyn software. Results of the analysis show that the hydraulic tensioner is incompatible with the timing drive system ofthe bush roller chain. Hence, the timing chain system causes a loud noise and strong vibration. Some strategies on how to optimize thetiming chain drive system are presented at the end of this paper.

Experimental and Numerical Research on the Laser Impact Welding of Ti/SS

Jiaxin Lu,Huixia Liu,Hao Jin,Feng Li,Xiaojun Wang,Xiao Wang 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.5

The welding of Ti/SS metal foil was realized by laser impact welding. The interface morphology and mechanical properties of welding specimens were studied by systematic experiments, and the experimental phenomena were revealed by smoothed particle hydrodynamics numerical simulation. Results indicated that the plastic deformation of the composite plate and the springback of the welding spot center were small under low laser pulse energy and enlarged under high laser pulse energy. Impinging jet, interface wave, and interface cracking were found at the micro-interface of the welding specimens. Increasing the laser pulse energy resulted in the transition of the interface waveform from straight to microwave and finally to wave primarily because of the change in interfacial impact pressure and effective plastic strain. Energy dispersive spectroscopy analysis showed that the trace element diff used at the welding interface, and no intermetallic compounds were formed. SPH simulation revealed that the thickness of the high-temperature layer was related to the thickness of the diffusion layer. As the distance between the test point and welding interface increased, the hardness decreased. The maximum tensile force of the welding specimens increased with laser pulse energy. The failure mode of the interface was welding spot edge fracture failure.

Seismic Response Investigation and Analyses of End Plate Moment-Resisting CFST Frames Under Pseudo-Dynamic Loads

Jingfeng Wang,Xuebei Pan,Xiao Peng,Jiaxin Wang 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.6

This paper reported an innovative semi-rigid composite frame comprised of concrete-fi lled steel tubular (CFST) columns and H-shaped steel beams assembled using fl ush or extended end plates with blind fasteners. Two specimens of two-story single-bay end plate moment-resisting square or circular CFST frames were investigated by a series of pseudo-dynamic tests. To analyze dynamic response of this type of structure under the earthquake action, time history response and story drift were investigated. The infl uence of the column section type and the end plate type on seismic performance of semirigid moment-resisting CFST frames under diff erent earthquake loading levels were also discussed according to hysteretic behavior, rigidity degradation and energy dissipation capacity. The experimental and analytical results indicated that at the same section width and steel ratio of the column, the rigidity of end plate moment-resisting square CFST frame was greater than that of circular CFST frame, while the story drift of square CFST frame was smaller than that of circular CFST frame. The type of end plate moment-resisting CFST frames with blind fasteners, which can provide good seismic behavior and energy dissipation ability, can be well used in a seismic region.

Isovitexin Is a Direct Inhibitor of Staphylococcus aureus Coagulase

( Hua Xiang ),( Panpan Yang ),( Li Wang ),( Jiaxin Li ),( Tiedong Wang ),( Junze Xue ),( Dacheng Wang ),( Hongxia Ma ) 한국미생물 · 생명공학회 2021 Journal of microbiology and biotechnology Vol.31 No.10

Staphylococcus aureus (S. aureus) is a major pathogen that causes human pneumonia, leading to significant morbidity and mortality. S. aureus coagulase (Coa) triggers the polymerization of fibrin by activating host prothrombin, which then converts fibrinogen to fibrin and contributes to S. aureus pathogenesis and persistent infection. In our research, we demonstrate that isovitexin, an active traditional Chinese medicine component, can inhibit the coagulase activity of Coa but does not interfere with the growth of S. aureus. Furthermore, we show through thermal shift and fluorescence quenching assays that isovitexin directly binds to Coa. Dynamic simulation and structure-activity relationship analyses suggest that V191 and P268 are key amino acid residues responsible for the binding of isovitexin to Coa. Taken together, these data indicate that isovitexin is a direct Coa inhibitor and a promising candidate for drug development against S. aureus infection.

Self-micro emulsifying formulation improved intestinal absorption and oral bioavailability of bakuchiol

Jiaxin Pi,Xu Gao,Yue Yu,Yin Zheng,Zhuangzhi Zhu,Yajing Wang 대한약학회 2021 Archives of Pharmacal Research Vol.44 No.9

Bakuchiol (BAK), isolated from the seeds ofPsoralea corylifolia L., recently presents a variety ofpharmacologic activities. However, the poor oral bioavailabilitylimits its further development and clinical use. The purpose of this study was to establish a self-microemulsifying(SME) formulation for oral deliveryimprovement of BAK. The optimized liquid SME formulationwas comprised of BAK (40 %), Cremophor RH 40(30 %) and Labrasol (30 %). The emulsion droplets werespherical in shape, and particle size and zeta potential weredetermined. The in vitro dissolution test of BAK-SMEformulation illustrated faster dissolution rate than the bulkdrug. The permeabilities of 40 lg mL-1 BAK-SME formulationin rat intestinal segments of duodenum, jejunum,ileum and colon were 30.91 9 10-3, 23.61 9 10-3,29.43 9 10-3 and 23.62 9 10-3 cm min-1, respectively,exhibiting 3.99 times in duodenum, 2.59 times in ileum and 2.31 times in colon greater than BAK perfusate. The oralbioavailability of BAK-SME formulation at a dose of150 mg kg-1 was determined in rats. The Cmax and theAUC(0–24h) were 515.4 ng mL-1 and 4,327.2 h ng mL-1,respectively, which were 1.90 fold and 1.73 fold greaterthan the value of BAK suspension. All these results clearlystated that BAK-SME formulation performed wellimprovementon oral bioavailability of BAK.

Ectopic expression of grape hyacinth R3 MYB repressor MaMYBx affects anthocyanin and proanthocyanidin biosynthesis and epidermal cell differentiation in Arabidopsis

Wang Jiangyu,Zhang Boxiao,Tian Shuting,Zhang Han,Gong Jiaxin,Chen Kaili,Du Lingjuan 한국원예학회 2022 Horticulture, Environment, and Biotechnology Vol.63 No.3

Single-repeat R3 MYB transcription factors regulate multiple developmental and metabolic pathways in plants. The anthocyanin-related R3 MYB repressor MaMYBx was previously identified in grape hyacinth (Muscari spp.), and its ectopic expression reduced the accumulation of anthocyanin in tobacco petals. However, whether the function of MaMYBx is conserved across plant species remains unclear. Here, we report that ectopic expression of MaMYBx regulates anthocyanin and proanthocyanidin (PA) biosynthesis and epidermal cell differentiation in Arabidopsis. MaMYBx overexpression in Arabidopsis decreased the accumulation of anthocyanin and PA by downregulating the late structural genes (AtDFR, AtANS, AtANR, and AtGST), some key regulatory factors of MBW complexes (AtPAP1, AtTT8, and AtGL3) and an R3 MYB gene (AtCPC) involved in flavonoid biosynthesis. In addition, MaMYBx also modulated trichome formation and root hair differentiation by downregulating MBW component genes (AtGL1, AtWER, and AtGL3) and their target gene AtGL2 and by upregulating several R3 MYB genes (AtTRY and AtTCL1). We further found that MaMYBx transgenic plants accumulated less anthocyanin than did wild-type plants under salt, osmotic pressure, cold, and nitrogen stresses. Moreover, the effect was even greater, and significantly less anthocyanin accumulated. In conclusion, these results implied functional conservation of MaMYBx in anthocyanin and PA biosynthesis pathways of Arabidopsis. Therefore, MaMYBx likely represents a new potential gene for the molecular breeding of horticulture and ornamental plants via the regulation of anthocyanin and PA.

Energy Efficient Hybrid Satellite Terrestrial 5G Networks with Software Defined Features

Jiaxin Zhang,Xing Zhang,Muhammad Ali Imran,Barry G. Evans,Yan Zhang,Wenbo Wang 한국통신학회 2017 Journal of communications and networks Vol.19 No.2

In order to improve the manageability and adaptabilityof future 5G wireless networks, the software orchestration mechanism,named software defined networking (SDN) with controland user plane (C/U-plane) decoupling, has become one of themost promising key techniques. Based on these features, the hybridsatellite terrestrial network is expected to support flexibleand customized resource scheduling for both massive machinetype-communication (MTC) and high-quality multimedia requestswhile achieving broader global coverage, larger capacity and lowerpower consumption. In this paper, an end-to-end hybrid satelliteterrestrial network is proposed and the performance metrics, e. g., coverage probability, spectral and energy efficiency (SE andEE), are analysed in both sparse networks and ultra-dense networks. The fundamental relationship between SE and EE is investigated,considering the overhead costs, fronthaul of the gateway(GW), density of small cells (SCs) and multiple quality-ofservice(QoS) requirements. Numerical results show that comparedwith current LTE networks, the hybrid system with C/U split canachieve approximately 40% and 80% EE improvement in sparseand ultra-dense networks respectively, and greatly enhance thecoverage. Various resource management schemes, bandwidth allocationmethods, and on-off approaches are compared, and theapplications of the satellite in future 5G networks with softwaredefined features are proposed.

Neoadjuvant chemotherapy followed by fertility-sparing surgery for women with stage IB1 cervical cancer

Dan Wang,Jiaxin Yang,Keng Shen,Yang Xiang 대한부인종양학회 2013 Journal of Gynecologic Oncology Vol.24 No.3

Fertility-sparing surgery was optimal to patients with tumor diameter smaller than 2 cm. For patients with larger tumors, neoadjuvant chemotherapy can debulk the tumor and offer the chance of surgery. We report 2 cases of stage IB1 cervical cancer treated by neoadjuvant chemotherapy and fertility-sparing surgery. Relevant literature was reviewed. Its safety, efficacy, and reproductive outcome need to be validated in the future.

HALF-METALLIC SILICENE AND GERMANENE NANORIBBONS: TOWARDS HIGH-PERFORMANCE SPINTRONICS DEVICE

YANGYANG WANG,JIAXIN ZHENG,ZEYUAN NI,RUIXIANG FEI,QIHANG LIU,RUGE QUHE,CHENGYONG XU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.5

By using first-principles calculations, we predict that an in-plane homogenous electrical ¯eld can induce half-metallicity in hydrogen-terminated zigzag silicene and germanene nanoribbons (ZSiNRs and ZGeNRs). A dual-gated ¯nite ZSiNR device reveals a nearly perfect spin-¯lter e±ciency (SFE)of up to 99% while a quadruple-gated ¯nite ZSiNR device serves as an effective spin ¯eld e®ect transistor (FET) with an on/o® current ratio of over 100 from ab initio quantum transport simulation. This discovery opens up novel prospect of silicene and germanene in spintronics.

Diabetes Mellitus and Cause-Specific Mortality: A Population-Based Study

Sen Li,Jiaxin Wang,Biao Zhang,Xinyi Li,Yuan Liu 대한당뇨병학회 2019 Diabetes and Metabolism Journal Vol.43 No.3

Background: To investigate whether diabetes contributes to mortality for major types of diseases. Methods: Six National Health and Nutrition Examination Survey data cycles (1999 to 2000, 2001 to 2002, 2003 to 2004, 2005 to 2006, 2007 to 2008, and 2009 to 2010) and their linked mortality files were used. A population of 15,513 participants was included according to the availability of diabetes and mortality status. Results: Participants with diabetes tended to have higher all-cause mortality and mortality due to cardiovascular disease, cancer, chronic lower respiratory diseases, cerebrovascular disease, influenza and pneumonia, and kidney disease. Confounder-adjusted Cox proportional hazard models showed that both diagnosed diabetes category (yes or no) and diabetes status (diabetes, prediabetes, or no diabetes) were associated with all-cause mortality and with mortality due to cardiovascular disease, chronic lower respiratory diseases, influenza and pneumonia, and kidney disease. No associations were found for cancer-, accidents-, or Alzheimer’s disease-related mortality. Conclusion: The current study’s findings provide epidemiological evidence that diagnosed diabetes at the baseline is associated with increased mortality risk due to cardiovascular disease, chronic lower respiratory diseases, influenza and pneumonia, and kidney disease, but not with cancer or Alzheimer’s disease.