Effects of Turbulent Dispersion on Water Droplet Impingement Based on Statistics Method

Ke Peng,Tang Xing,Lu Yi,Yang Hui Yun 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.2

Researchonthewaterdropletmotionandimpactonsurfaceisthebasisofaircrafticingpredictionanddesignoficeprotection system. First, a new computational method based on statistical theory was developed in the Euler–Lagrange framework to calculatethelocalwaterimpingementcoefficientonthesurface,whichcouldbeusedtostudytheeffectofturbulentdispersion onthewaterdropletmotionandimpingementcharacteristics.Second,basedontheRANSmodelfortheairflowfield,taking engineconesurfacewithorwithoutslotasexamples,theinfluenceofturbulentdispersiononthewaterimpingementcoefficient on the surface was comparatively analyzed with the discrete random walk model. For the cone without film slot, turbulence causes a little impact on water droplet impingement. However, for the slotted cone, water droplet collection calculation must consider the effect of turbulence due to the stronger turbulence induced by the jet air. Further studies show that the effect is enhanced with the decrease of water droplet diameter. Finally, discussion about turbulent effects was proposed. This researchabout theinfluence ofturbulentdispersionwillbehelpfultoimprovetheaccuracy ofthewaterdropletimpingement calculation for some complex geometries.

Effects of Turbulent Dispersion on Water Droplet Impingement Based on Statistics Method

Peng, Ke,Xing, Tang,Yi, Lu,Yun, Yang Hui The Korean Society for Aeronautical Space Sciences 2018 International Journal of Aeronautical and Space Sc Vol.19 No.2

Research on the water droplet motion and impact on surface is the basis of aircraft icing prediction and design of ice protection system. First, a new computational method based on statistical theory was developed in the Euler-Lagrange framework to calculate the local water impingement coefficient on the surface, which could be used to study the effect of turbulent dispersion on the water droplet motion and impingement characteristics. Second, based on the RANS model for the air flow field, taking engine cone surface with or without slot as examples, the influence of turbulent dispersion on the water impingement coefficient on the surface was comparatively analyzed with the discrete random walk model. For the cone without film slot, turbulence causes a little impact on water droplet impingement. However, for the slotted cone, water droplet collection calculation must consider the effect of turbulence due to the stronger turbulence induced by the jet air. Further studies show that the effect is enhanced with the decrease of water droplet diameter. Finally, discussion about turbulent effects was proposed. This research about the influence of turbulent dispersion will be helpful to improve the accuracy of the water droplet impingement calculation for some complex geometries.

Mortality of Urinary Tract Cancer in Inner Mongolia 2008-2012

Xin, Ke-Peng,Du, Mao-Lin,Li, Zhi-Jun,Li, Yun,Li, Wuyuntana,Su, Xiong,Sun, Juan Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.6

The aim of this study was to determine the mortality rate and burden of urinary tract cancers among residents of Inner Mongolia. We analyzed mortality data reported by the Death Registry System from 2008 to 2012. The rate of mortality due to urinary tract cancer was 2.04 per 100,000 person-years for the total population, 2.91 for men, and 1.11 for women. Therefore, the mortality rate for men was 2.62-fold the mortality rate for women, constituting a statistically significant difference (p<0.001). Over the period 2008 through 2012, the total potential years of life lost was 1388.1 person-years for men and 777.1 person-years for women, and the average years of life lost were 7.71 years per male decedent and 12.0 years per female decedent. Mortality due to urinary tract cancers is substantially greater among the elderly population. Further, the mortality rate associated with urinary tract cancers is greater for elderly men than it is for elderly women. Therefore, in Inner Mongolia, urinary tract cancers appear to pose a greater mortality risk for men than they do for women.

Molecular Cloning, Bioinformatics Analysis and Expression Profiling of a Gene Encoding Vacuolar-type H(+) -ATP Synthetase (V-ATPase) c Subunit from Bombyx mori-

( Peng Lii ),( Ke Ping Chen ),( Hua Jun Yang ),( Qin Yao ) 한국잠사학회 2007 International Journal of Industrial Entomology Vol.15 No.2

As the genome of B.mori is available in GenBank and the EST database of B.mori is expanding, identification of novel genes of B.mori is conceivable by data-mining techniques. We used the in silico cloning method to get the vacuolar-type H(+)-ATP synthetase (V-ATPase) c subunit (16 kDa proteolipid subunit) gene of B.mori and analysed with bioinformatics tools. The result was confirmed by RT-PCR and sequencing. The V-ATPase c subunit cDNA contains a 468bp ORF. The ORF encoded a 155-residue protein that showed extensive homology with V-ATPase c subunits from other 15 species and contained four membrane-spanning helices. Tissue expression pattern analysis revealed that V-ATPase c expressed strongly in Mal-pighian tubules, not in fat body. This gene has been registered in GenBank under the accession number EU082222.

Influence of Device Parameters Spread on Current Distribution of Paralleled Silicon Carbide MOSFETs

Ke, Junji,Zhao, Zhibin,Sun, Peng,Huang, Huazhen,Abuogo, James,Cui, Xiang The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.4

This paper systematically investigates the influence of device parameters spread on the current distribution of paralleled silicon carbide (SiC) MOSFETs. First, a variation coefficient is introduced and used as the evaluating norm for the parameters spread. Then a sample of 30 SiC MOSFET devices from the same batch of a well-known company is selected and tested under the same conditions as those on datasheet. It is found that there is big difference among parameters spread. Furthermore, comprehensive theoretical and simulation analyses are carried out to study the sensitivity of the current imbalance to variations of the device parameters. Based on the concept of the control variable method, the influence of each device parameter on the steady-state and transient current distributions of paralleled SiC MOSFETs are verified separately by experiments. Finally, some screening suggestions of devices or chips before parallel-connection are provided in terms of different applications and different driver configurations.

A High-Robust Grid-Side Current Feedback Active Damping Design Method for Gridconnected Inverter

Ke Xu,Li Peng,Weibiao Wu,Bowei Lin,Shirong Yang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Grid-connected inverter with LCL filter is widely employed in renewable energy generation system due to high harmonic suppression ability. However, the resonance issue caused by LCL filter is brought easily. To solve this issue, grid-side current feedback active damping control strategy based on proportional derivative algorithm is employed for cost consideration. Taking digital control delay time into consideration, the active damping method is analyzed in discrete domain. A parameter design method based on dominant pole optimization is proposed, which can not only enhance damping ability but also achieve high robust performance. The validity of the proposed method is finally confirmed by the experimental results.

Bistable Phenomenon of Discharge in a Hall Plasma Accelerator

Ke Han,Peng E,Yongkai Liu,Yanchao Ji 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

An interesting phenomenon observed in a Hall plasma accelerator operated in self-excited mode is that the discharge current jumps to-and-fro between two different values. This phenomenon is named bistable characteristic of discharge current. Experimental results show that the discharge current bistable characteristic happens in a narrow range of anode mass flow rate, while the current is stable at one value and almost linear to mass flow rate in other wide range. It is indicated that there is invalidation control region by adjusting anode mass flow rate to stabilize the discharge current in flight-type Hall plasma accelerators. In addition, the physical mechanism of this phenomenon is researched and a steady method is presented through analyzing the characteristics of all intersection points of magneto-ampere characteristic curve and magnetic field coil current curve in a Hall plasma accelerator.

MiR-214 Regulates the Human Hair Follicle Stem Cell Proliferation and Differentiation by Targeting EZH2 and Wnt/b- Catenin Signaling Way In Vitro

Ke-Tao Du,Jia-Qin Deng,Xu-Guang He,Zhao-ping Liu,Cheng Peng,Mingsheng Zhang 한국조직공학과 재생의학회 2018 조직공학과 재생의학 Vol.15 No.3

miR-214 plays a major role in the self-renewal of skin tissue. However, whether miR-214 regulates the proliferation and differentiation of human hair follicle stem cells (HFSCs) is unknown. Primary HFSCs were isolated from human scalp skin tissue, cultured, and identified using flow cytometry. An miR-214 mimic and inhibitor were constructed for transfection into HFSCs. The MTS and colony formation assays examined cell proliferation. Immunofluorescence detected the localization and expression levels of TCF4, b-catenin, and differentiation markers. Luciferase reporter and TOP/FOP Flash assays investigated whether miR-214 targeted EZH2 and regulated the Wnt/b-catenin signaling pathway. Western blot determined the expression levels of enhancer of zeste homolog 2 (EZH2), Wnt/b-catenin signaling-related proteins, and HFSC differentiation markers in cells subjected to miR-214 transfection. miR-214 expression was remarkably decreased during the proliferation and differentiation of HFSCs into transit-amplifying (TA) cells. Downregulation of miR- 214 promotes the proliferation and differentiation of HFSCs. Overexpression of miR-214 led to decreased expression of EZH2, b-catenin, and TCF-4, whereas downregulation of miR-214 resulted in increased expression of EZH2, b-catenin, and TCF-4 as well as TA differentiation markers. Immunofluorescence assay revealed that inhibiting miR-214 triggered the entry of b-catenin and TCF-4 into the nucleus. The luciferase reporter and TOP/FOP Flash assays demonstrated that miR- 214 directly targets EZH2 and affects Wnt/b-catenin signaling. The miR-214/EZH2/b-catenin axis could be considered a candidate target in tissue engineering and regenerative medicine for HFSCs.

Friction Stir Processing of Cold-Sprayed High-Entropy Alloy Particles Reinforced Aluminum Matrix Composites: Corrosion and Wear Properties

Peng Han,Jia Lin,Wen Wang,Zhihao Liu,Yating Xiang,Ting Zhang,Qiang Liu,Xiaohu Guan,Ke Qiao,Yingchun Xie,Kuaishe Wang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.3

The high-entropy alloy particles reinforced 6061Al composite was prepared by cold spray (CS) and then modified by frictionstir processing (FSP). The microstructure evolutions, corrosion, and wear behaviors of the composites were investigated. Results showed that numerous micro-pores and cracks were distributed in the Al matrix due to adiabatic shear instability andinsufficient deformation of the deposited particles for CSed samples. The average size of uniformly distributed HEA particleswas ~ 24 μm, and the geometric necessary dislocation (GND) density reached 17.1 × 1015m−2 due to large plastic deformationduring CS. Comparatively, the micro-pores and cracks were eliminated, and many fragmented HEA particles dispersed inthe Al matrix with an average size of ~ 4 μm for FSPed sample. Note that the GND density reduced to 9.8 × 1015m−2 due todynamic recrystallization during FSP. The formation rate of the oxide film was gradually greater than that of the dissolutionrate with the samples immersion in 3.5 wt% NaCl solution from 12 to 36 h, and the main corrosion mechanism was particledissolution around micro-pores and pitting for CSed and FSPed samples, respectively. In the polarization process, the FSPedsamples exhibited low corrosion tendency and high corrosion rate due to the dense and uniform microstructure, low GNDdensity, and dispersed HEA particles. The FSPed samples had better wear resistance than the CSed samples at 25 °C and200 °C. The dominant wear mechanisms of CSed and FSPed samples were abrasion at 25 °C, while the wear mechanismsof these samples were adhesion accompanied by abrasion at 200 °C.

Enhancing Tensile Properties of Wire-Arc Additively Manufactured Ti-6Al-4 V Deposits Via Cryogenic Vaporised Ar Shielding/Cooling

Peng Han,Jia Lin,Wen Wang,Zhihao Liu,Yating Xiang,Ting Zhang,Qiang Liu,Xiaohu Guan,Ke Qiao,Yingchun Xie,Kuaishe Wang 대한금속ᆞ재료학회 2023 METALS AND MATERIALS International Vol.29 No.2

The high-entropy alloy particles reinforced 6061Al composite was prepared by cold spray (CS) and then modified by frictionstir processing (FSP). The microstructure evolutions, corrosion, and wear behaviors of the composites were investigated. Results showed that numerous micro-pores and cracks were distributed in the Al matrix due to adiabatic shear instability andinsufficient deformation of the deposited particles for CSed samples. The average size of uniformly distributed HEA particleswas ~ 24 μm, and the geometric necessary dislocation (GND) density reached 17.1 × 1015m−2 due to large plastic deformationduring CS. Comparatively, the micro-pores and cracks were eliminated, and many fragmented HEA particles dispersed inthe Al matrix with an average size of ~ 4 μm for FSPed sample. Note that the GND density reduced to 9.8 × 1015m−2 due todynamic recrystallization during FSP. The formation rate of the oxide film was gradually greater than that of the dissolutionrate with the samples immersion in 3.5 wt% NaCl solution from 12 to 36 h, and the main corrosion mechanism was particledissolution around micro-pores and pitting for CSed and FSPed samples, respectively. In the polarization process, the FSPedsamples exhibited low corrosion tendency and high corrosion rate due to the dense and uniform microstructure, low GNDdensity, and dispersed HEA particles. The FSPed samples had better wear resistance than the CSed samples at 25 °C and200 °C. The dominant wear mechanisms of CSed and FSPed samples were abrasion at 25 °C, while the wear mechanismsof these samples were adhesion accompanied by abrasion at 200 °C.