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Chinese Journal of Aeronautics 2022年第3期35卷 494-508页

作者： Minghuan WANG Yongchao SHANG Changshun LIU Jiajie WANG Jinsong ZHENG xufeng xu College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310023ZhejiangChina Key Laboratory of Special Purpose Equipment and Advanced Processing Technology of Ministry of Education Zhejiang University of TechnologyHangzhou 310023ZhejiangChina

The radial ultrasonic rolling electrochemical micromachining(RUR-EMM)combined rolling electrochemical micromachining(R-EMM)and ultrasonic vibration was studied in this *** fundamental understanding of the machining process especially the interaction between multiphysics in the interelectrode gap(IEG)was investigated and discussed by the finite element *** multiphysics coupling model including flow field model,Joule heating model,material dissolution model and vibration model was built.3D multiphysics simulation based on micro dimples process in RUR-EMM and R-EMM was *** results showed that the electrolyte flowed into and out IEG periodically,gas bubbles were easy to squeeze out and the gas void fraction deceased about 16%to 54%,the maximum current density increased by 1.36 times in RUR-EMM than in R-EMM in one vibration period of *** application of the ultrasonic vibration increased the electrolyte temperature about 1.3–4.4%in *** experiments of the micro dimple process denoted better corrosion consistency of array dimples in RUR-EMM,there was no island at the micro dimple bottom which always formed in R-EMM,and an aggregated deviation of less than 8.7%for the micro dimple depth and 4%for the material removal amount between theory and experiment was obtained.

关键词： 3D Multiphysics simulation Electrochemical micromachining Energy field Material process Micro dimple Ultrasonic vibration

Study of Linear and Nonlinear Optical Properties of Four Derivatives of Substituted Aryl Hydrazones of 1,8-Naphthalimide

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Chinese Journal of Chemistry 2014年第3期32卷 205-211页

作者： Peiyang Gu xufeng xu Feng Zhou Tingting Zhao Gaojie Ye Gaoyan Liu Qinghua xu Jianfeng Ge Qingfeng xu Jianmei Lu Department of Polymer Science College of ChemistryChemical Engineering and Materials ScienceSoochow UniversitySuzhouJiangsu 215123China Department of Chemistry National University of Singapore3 Science Drive 3117543Singapore

Four 1,8-naphthalimide hydrazone molecules with different electron-donating groups have been applied in the study of linear and nonlinear optical(NLO)*** compounds showed strong green emission in *** NLO properties such as two-photon absorption(TPA)behavior with femtosecond laser pulses ca.800 nm and excited-state absorption(ESA)behavior with nanosecond laser pulses at 532 nm were *** 4 presented the largest two-photon cross section(550 GM)among them due to two factors:the conjugated length of compound 4 is the longest and the electron-donating ability of compound 4 is the *** from TPA behavior,compound 2 showed the best nonlinear absorption properties at 532 nm and its nonlinear absorption coef-ficient and third-order nonlinear optical susceptibilitiesχ^(3)were up to 1.41×10^(−10) MKS and 4.65×10^(−12) esu,*** the modification of the structure,the nonlinear optical properties of these compounds at differ-ent wavelengths(532 and 800 nm)were well *** great broad-band nonlinear optical properties indicate hy-drazones are good candidates for organic nonlinear optical absorption materials.

关键词： excited-state absorption(ESA) fluorescence naphthalimide nonlinear optical(NLO) two-photon absorption(TPA)

Preparation and properties of hollow fibre nanofiltration membrane with continuous coffee-ring structure

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Frontiers of Chemical Science and Engineering 2021年第2期15卷 351-362页

作者： Xiuzhen Wei xufeng xu Yi Chen Qian Zhang Lu Liu Ruiyuan Yang Jinyuan Chen Bosheng Lv College of Environment Zhejiang University of TechnologyHangzhou 310014China Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province Hangzhou 310014China

Polyamide(PA)hollow fibre composite nanofiltration(NF)membranes with a coffee-ring structure and beneficial properties were prepared by adding graphene oxide(GO)into the interfacial polymerization *** presentation of the coffee-ring structure was attributed to the heterogeneous,finely dispersed multiphase reaction system and the“coffee-stain”effect of the GO *** the piperazine concentration was 0.4 wt-%,the trimesoyl chloride concentration was 0.3 wt-%,and the GO concentration was 0.025 wt-%,the prepared NF membranes showed the best separation *** permeate flux was 76 L·m^(−2)·h^(−1),and the rejection rate for MgSO4 was 98.6%at 0.4 *** electron microscopy,atomic force microscopy,and attenuated total reflectance-Fourier transform infrared spectroscopy were used to characterize the chemical structure and morphology of the PA/GO NF *** results showed that GO was successfully entrapped into the PA functional *** neutral operating conditions,the PA/GO membrane showed typical negatively charged NF membrane separation characteristics,and the rejection rate decreased in the order of Na2SO_(4)>MgSO_(4)>MgCl_(2)>*** PA/GO NF membrane showed better antifouling performance than the PA membrane.

关键词： GO PA interfacial polymerization hollow fibre NF membrane

Experimental investigation on the spray characteristics of agricultural full-cone pressure swirl nozzle

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International Journal of Agricultural and Biological Engineering 2023年第4期16卷 29-40页

作者： Xiuyun xue xufeng xu Shilei Lyu Shuran Song Xin Ai Nengchao Li Zhenyu Yang Zhen Li College of Electronic Engineering(College of Artificial Intelligence) South China Agricultural UniversityGuangzhou 510642China National Citrus Industry Technical System Machinery Research Office Guangzhou 510642China Engineering Research Center for Monitoring Agricultural Information of Guangdong Province Guangzhou 510642China Meizhou SCAU-Zhensheng Research Institute for Modern Agricultural Equipment Meizhou 514781China

The spray characteristics of a full-cone pressure swirl nozzle have been investigated in this *** results were defined by Reynolds number,which focuses on the breakup of liquid film,droplet size,velocity,and liquid volume flux under different Reynolds numbers at the near-field *** spray structure was visualized using a high-speed camera,and the characteristics of droplets were measured using a Phase Doppler Anemometer(PDA)in both the radial and axial *** tests were carried out at varying spray pressures(0.2 to 1.0 MPa),corresponding to different Reynolds numbers(5369 to 12006).It was found that when the Reynolds number rises,the liquid became more unstable after leaving the nozzle,causing the liquid film to break up *** to the measurements of PDA,the coalescence of droplets increased due to the centrifugal ***’s more,the velocity of the droplets fluctuates significantly in the radial direction,and the droplets with a smaller particle size had a higher average *** the perspective of liquid distribution,the increase in Reynolds number caused the spray liquid to move in the radial direction *** contrast,the liquid volume distribution changed in the radial direction more obviously than in the axial direction,growing to the maximum along the radial direction and gradually *** can provide a reference for selecting operating parameters for actual agricultural spray operations and the design of electrostatic nozzles through the research on breakup and droplet characteristics.

关键词： full-cone pressure swirl nozzle droplet size droplet velocity liquid volume flux high-speed camera PDA

Assessment of Operating Condition Dependent Reliability Indices in Microgrids

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Journal of Power and Energy Engineering 2016年第4期4卷 56-66页

作者： Rafael Medeiros xufeng xu Elham Makram Department of Electrical and Computer Engineering Clemson University Clemson SC USA

Reliability results are important for proper planning and operation of utility companies. At the base of this method of analysis is the failure rate of the system components. In the traditional method, this probability of failure is determined by the components’ manufacturer and is considered to be constant. This study proposes a dynamic modeling of failure rate, taking the system operating conditions into consideration. With this new consideration, an IEEE test system has seven of its reliability indices quantified for comparison. The inclusion of the newly modeled failure rate leads to a worsening of 11.07% in the indices, on average. A second analysis is performed considering the presence of DG sources within the microgrid, namely PV and wind based. An improvement of 0.71% on the indices is noticed, once the DG sources are introduced. Finally, the effects of storage systems in the microgrid are investigated through a third scenario, in which two 2 MWh battery systems are introduced, and an improvement of 3.05% is noticed in the reliability indices.

关键词： Failure Rate Microgrid Power Flow Reliability Assessment Renewables Storage

Impacts of Water-Tree Fault on Ferroresonance in Underground Cables

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Journal of Power and Energy Engineering 2017年第12期5卷 75-86页

作者： Bin Sun Elham Makram xufeng xu Electrical and Computer Engineering Department Clemson University Clemson USA

Nowadays, more and more electrical power is being distributed to customers by underground cables rather than overhead transmission lines due to their advantage of providing better protection in inclement weather. They also have significantly reduced electromagnetic field emission because of their copper shielding. But underground cables have larger capacitance than transmission lines per unit. Thus, ferroresonance is more likely to occur in distribution systems using underground cables. Moreover, soil humidity at a depth of one meter remains 100 percent for most of the year, a factor that risks the occurrence of water tree (WT) in cables. Consequently, both ferroresonance and WT are prone to occur in underground cable systems. The objective of this paper is to determine the relationship between ferroresonance and water tree. A test system was designed to simulate and analyze ferroresonance in a cable system caused by single-phase switch and water tree. Eight scenarios of water tree were compared in the simulation. There sponses of ferroresonance are presented in this paper and two common patterns are observed from the simulation results.

关键词： Ferroresonance Water Tree PSCAD COMSOL Overvoltage

Androgen-deprivation therapy-induced aggressive prostate cancer with neuroendocrine differentiation

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Asian Journal of Andrology 2014年第4期16卷 541-544页

作者： Julia Lipianskaya Alexa Cohen Clark J Chen Elaine Hsia Jill Squires Zhen Li Yaqun Zhang Wei Li xufeng Chen Hua xu Jiaoti Huang Departments of Pathology and Urology Jonsson Comprehensive Cancer Center and Broad Center of Regenerative Medicine and Stem Cell Research David Geffen School of Medicine at UCLA Los Angeles CA USA.

Most prostate cancers （PCas） are classified as acinar type （conventional） adenocarcinoma which are composed of tumor cells with luminal differentiation including the expression of androgen receptor （AR） and prostate-specific antigen （PSA）. There are also scattered neuroendocrine （NE） cells in every case of adenocarcinoma. The NE cells are quiesecent, do not express AR or PSA, and their function remains unclear. We have demonstrated that IL8-CXCR2-P53 pathway provides a growth-inhibitory signal and keeps the NE cells in benign prostate and adenocarcinoma quiescent. Interestingly, some patients with a history of adenocarcinoma recur with small cell neuroendocrine carcinoma （SCNC） after hormonal therapy, and such tumors are composed of pure NE cells that are highly proliferative and aggressive, due to P53 mutation and inactivation of the IL8-CXCR2-P53 pathway. The incidence of SCNC will likely increase due to the widespread use of novel drugs that further inhibit AR function or intratumoral androgen synthesis. A phase II trial has demonstrated that platinum-based chemotherapy may be useful for such therapy-induced tumors.

关键词： neuroendocrine prostate cancer small cell carcinoma therapy

The Impact of the Offshore Wind Farm Switching Transient Operation on Power System

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Journal of Power and Energy Engineering 2014年第8期2卷 14-24页

作者： Tingting Wang Elham Makram Ramtin Hadidi xufeng xu Electrical and Computer Engineering Department Clemson University Clemson USA

In this paper, a practical method to establish Doubly Fed Induction Generator (DFIG) based wind farm equivalent model for switching transient analysis is demonstrated. In order to verify this method, a 3.6MW equivalent wind farm model is built. The steady state results and load switching results are verified with those of detailed models of four 0.9MW generators. Using this method, a model of 40MW wind farm, representing the capacity for a proposed South Carolina offshore wind farm is established. To study large wind farm switching transient impacts on a system, different switching operations such as cable energizing and three phase faults at different locations in wind farm are investigated and their impact on system are analysed. Finally, conclusions based on the switching cases are presented.

关键词： Offshore Wind Farm DFIG Switching Transient Load Switching Capacitor Switching Fault

Power System Harmonics Study for Unbalanced Microgrid System with PV Sources and Nonlinear Loads

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Journal of Power and Energy Engineering 2015年第5期3卷 43-55页

作者： Zhanhe Liu xufeng xu Hany A. Abdelsalam Elham Makram Electrical and Computer Engineering Department Clemson University Clemson USA Electrical Engineering Department Kafrelshikh University Kafrelshikh Egypt

Harmonics distortion is a crucial problem in microgrid. Harmonic sources can be categorized as two main factors: renewable energy integration and nonlinear loads. Both factors are investigated in this paper. For renewbale energy, photovoltaic (PV) power is one of the most effective solutions for energy crisis and it is showing great potential for serving customers in microgrid. A three- phase PV source model is establised and integrated at different locations in order to observe the impact of harmonics on a microgrid and power quality (PQ). A composite load is modeled using Crossed Frequency Admittance Matrix theory. A practicdal microgrid loacated at GA, USA is used as a study system. The microgrid, PV model and nonlinear load model are simulated in MATLAB/ Simulink environment. The results show the impact of installing PV sources at two types of locations considering linear and composite nonlinear loads. In addition, three PQ indices are discussed to show the numerical impacts with various perspectives.

关键词： Crossed Frequency Admittance Matrix Nonlinear Load Harmonics Distortion PV Power Quality Indices

Capacitance of Water Tree Modeling in Underground Cables

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Journal of Power and Energy Engineering 2014年第11期2卷 9-18页

作者： Qi Chen Klaehn Burkes Elham Makram Ramtin Hadidi xufeng xu Department of Electrical Engineering Clemson University Clemson USA

Water Tree is a corrosion phenomenon in cross-link polyethylene (XLPE) insulation. It is commonly found in underground cables. Water tree induced fault is difficult to detect due to its high impedance and difficult to model due to its random nature. In recent years, underground cables have become more popular in the power industry. They are resistant to environmental damage and has reduced space requirement. They are suitable to areas with high environment hazard or heavily populated areas where space is a constraining factor. As a result, studying and modeling the structure and effect of water tree become increasingly important. Since majority of the fault inducing water trees are vented trees which originated from the surface of the cable insulation, the mathematical model focuses on this particular type of water tree. To reduce the complexity of the model, the shape of the water tree afflicted region of the insulation is assumed to be ellipsoidal and the permittivity of the region is assumed to be linearly changing. Finite element analysis is used to analyze the water tree affected region. The resultant capacitance is calculated and compared with a physical model from Comsol. The result obtained using the proposed mathematical model and the result obtained using physical simulation through Comsol package agrees with each other. Hence, this method can be used to analyze the effect of water tree fault in large power systems.

关键词： Water Tree Vented Tree Finite Elemental Analysis Capacitance