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Boundary Behavior of Large Solutions to the Monge–Ampère Equation in a Borderline Case

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Acta Mathematica Sinica,English Series 2019年第7期35卷 1190-1204页

作者： Zhi jun zhang School of Mathematics and Information Science Yantai University

This paper is concerned with the boundary behavior of strictly convex large solutions to the Monge–Ampère equation det D^2u(x) = b(x)f(u(x)), u >0, x∈Ω, where Ω is a strictly convex and bounded smooth domain in R^N with N ≥ 2, f is normalized regularly varying at infinity with the critical index N and has a lower term, and b∈C~∞(Ω) is positive in Ω, but may be appropriate singular on the boundary.

关键词： The Monge–Ampère equations strictly convex large solutions a borderline case boundary behavior

真空预冷压强对鲜枸杞SOD酶活性的影响及分子动力学模拟

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食品工业科技 2025年第1期46卷 54-60页

作者：张宏博康宁波周良欢张军瞿前进宁夏大学食品科学与工程学院宁夏银川750021

为探究真空预冷处理对鲜枸杞超氧化物歧化酶(superoxide dismutase,SOD)活性的影响及其分子水平机理,本研究将宁夏新鲜枸杞置于真空预冷900、1100 Pa压强下处理,提取粗酶液进行SOD酶活性测定,并进行150 ns分子动力学模拟研究SOD酶在不... 详细信息

为探究真空预冷处理对鲜枸杞超氧化物歧化酶(superoxide dismutase,SOD)活性的影响及其分子水平机理,本研究将宁夏新鲜枸杞置于真空预冷900、1100 Pa压强下处理,提取粗酶液进行SOD酶活性测定,并进行150 ns分子动力学模拟研究SOD酶在不同真空预冷压强处理下的内部变化,分析均方根误差、回旋半径、总能量、势能、动能、键角能、均方根涨落、氢键数量、表面结构、溶剂可及表面积的改变,进而筛选出真空预冷处理的最佳压强条件。结果显示,900 Pa处理下SOD酶活最高。分子动力学模拟结果表明,体系总能量、势能、动能及键角能均处于平衡稳定状态,压强增大使得蛋白质表面结构改变,氢键数量减少,溶剂可及表面积不断减小。在900 Pa处理下,蛋白质结构最紧密,活性口袋变宽且易与蛋白结合。而1100 Pa处理下酶蛋白活性降低,蛋白结构破坏,活性口袋变小。本研究可为研究鲜枸杞保鲜及加工提供科学参考。

关键词：枸杞真空预冷超氧化物歧化酶分子动力学模拟

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Modeling droplet vaporization and combustion with the volume of fluid method at a small Reynolds number

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第5期13卷 361-374页

作者： Xiao-bin zhang Wei zhang Xue-jun zhang Institute of Refrigeration and Cryogenics Zhejiang University Hangzhou 310027 China

The volume of fluid(VOF) formulation is applied to model the combustion process of a single droplet in a hightemperature convective air free stream *** calculations solve the flow field for both phases,and consider the droplet deformation based on an axisymmetrical *** chemical reaction is modeled with one-step finite-rate mechanism and the thermo-physical properties for the gas mixture are species and temperature dependence.A mass transfer model applicable to the VOF calculations due to vaporization of the liquid phases is developed in consideration with the fluctuation of the liquid *** model is validated by examining the burning rate constants at different convective air temperatures,which accord well with experimental data of previous *** phenomena from the simulations,such as the transient history of droplet deformation and flame structure,are also qualitatively accordant with the descriptions of other numerical ***,a different droplet deformation mechanism for the low Reynolds number is explained compared with that for the high Reynolds *** calculations verified the feasibility of the VOF computational fluid dynamics(CFD) formulation as well as the mass transfer model due to vaporization.

关键词： Droplet Vaporization Combustion process Volume of fluid(VOF) Numerical simulation

Detecting nanoparticles by“listening”

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Frontiers of physics 2023年第5期18卷 113-131页

作者： Haonan Chang jun zhang State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

In the macroscopic world,we can obtain some important information through the vibration of objects,that is,listening to the ***,we can also get some information of the nanoparticles that we want to know by the means of“listening”in the microscopic *** this review,we will introduce two sensing methods(cavity optomechanical sensing and surface-enhanced Raman scattering sensing)which can be used to detect the *** cavity optomechanical systems are mainly used to detect sub-gigahertz nanoparticle or cavity vibrations,while surface-enhanced Raman scattering is a well-known technique to detect molecular vibrations whose frequency generally exceeds ***,the vibrational information of nanoparticles from low-frequency to high-frequency could be obtained by these two *** size of the viruses is at the nanoscale and we can regard it as a kind of *** and ultrasensitive detection of the viruses is the key strategies to break the spread of the viruses in the *** optomechanical sensing enables rapid,ultrasensitive detection of nanoparticles through the interaction of light and mechanical oscillators and surface-enhanced Raman scattering is an attractive qualitatively analytical technique for chemical sensing and biomedical applications,which has been used to detect the SARS-CoV-2 ***,investigation in these two fields is of vital importance in preventing the spread of the virus from affecting human’s life and health.

关键词： ultrasensitive sensing cavity optomechanics surface-enhanced Raman scattering

Addition formulae, Backlund transformations, periodic solutions, and quadrilateral equations

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Frontiers of Mathematics in China 2019年第1期14卷 203-223页

作者： Danda zhang Da-jun zhang School of Mathematics and Statistics Ningbo University Ningbo 315211 China Department of Mathematics Shanghai University Shanghai 200444 China

Addition formulae of trigonometric and elliptic functions are used to generate Backlund transformations together with their connecting quadrilateral equations. As a result, we obtain the periodic solutions for a numbe... 详细信息

关键词： Addition formulae trigonometric functions elliptic functions Backlund transformation quadrilateral equations

Effects of Measuring Positions on the Measured Aerodynamic Performance of a Centrifugal Compressor

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Journal of Thermal Science 2010年第2期19卷 110-114页

作者： Hongwei MA jun zhang School of Jet Propulsion Beihang University Beijing 100191 China National Key Laboratory of Science and Technology on Aero-Engines Beijing 100191 China

This paper performs a numerical simulation of three-dimensional flow field in a centrifugal compressor with long inlet and outlet pipes using CFX *** arranging virtual probes at different positions in both inlet and outlet planes,the aerodynamic performance of the centrifugal compressor is measured and compared with each *** effects of measuring positions on measurement results are *** results show that it will generate notable measuring errors of the pressure ratio and efficiency if the inlet total pressure is measured using a single-point *** inlet total pressure data can be accurate when they are measured using a 3-point *** outlet total pressure and total temperature data can not be accurate if they are respectively measured at one circumferential position even using a multi-point *** tangential measuring positions at the outlet is effective to improve the test *** the outlet total pressure and total temperature are respectively measured at 3 tangential positions,the data can be almost accurate.

关键词： centrifugal compressor aerodynamics performance measuring error measurement position probe.

Composition and Microstructure of Magnetron Sputtering Deposited Ti-containing Amorphous Carbon Films

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Journal of Materials Science & Technology 2007年第4期23卷 571-573页

作者： jun DU Ping zhang National Key Laboratory for Remanufacturing Academy of Armored Force Engineering Beijing 100072 China

Ti-containing carbon films were deposited by using magnetron sputtering deposition. The composition and microstructure of the carbon films were characterized in detail by combining the techniques of Rutherford backscattering spectrometry （RBS）, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. It is found that carbon films contain Ti 18 at pct; after Ti incorporation, the films consist of titanium carbide; C1s peak appears at 283.4 eV and it could be divided into 283.29 and 284.55 eV, representing sp2 and sp3, respectively, and sp2 is superior to sp3. This Ti-containing film with dominating sp2 bonds is nanocomposites with nanocrystalline TiC clusters embedded in an amorphous carbon matrix, which could be proved by XRD and TEM.

关键词： Magnetron sputtering deposition Carbon film, Carbon bond structure

Effects of pruning intensity on nonstructural carbohydrates of Populus alba×*** in the arid desert region of Northwest China

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Journal of Forestry Research 2021年第2期32卷 823-830页

作者： jun zhang Liqing Liu School of Forestry Northeast Forestry UniversityHarbin 150040People’s Republic of China College of Forestry and Horticulture Xinjiang Agricultural UniversityÜrümqi 830052People’s Republic of China Xinjiang Tianxi Environmental Protection Technology Co.Ltd Ürümqi 830000People’s Republic of China

Although pruning is important to obtain highquality,large-diameter timber,the effects of pruning on nonstructural carbohydrates(NSC)in aboveground organs of many timber species are not well *** intensities of pruning(none,moderate and severe)were tested on poplars(Populus alba×***)in the arid desert region of northwest China to compare the concentrations of soluble sugar(SS),starch(ST)and total nonstructural carbohydrate(TNC)in leaves,branches and trunks during the growing *** concentration of NSC components after different pruning intensities varied similarly in seasonal patterns,increasing slowly at the beginning of the growing season,continuously declining in the middle,then gradually recovering by the end of the growing *** monthly mean NSC concentration in poplar differed significantly among the three pruning intensities(pbranch>trunk,while the order of ST concentration was trunk>leaf>branch,which was related to functional differences of plant *** annual average growth in height of unpruned,moderately pruned,and severely pruned poplars was 0.21±0.06,0.45±0.09 and 0.24±0.05 m,respectively,and the annual average growth in DBH were 0.92±0.04,1.27±0.06 and 1.02±0.05 cm,*** results demonstrate that moderate pruning may effectively increase the annual growth in tree height and DBH while avoiding damage caused by excessive pruning to the tree ***,moderate pruning may increase the NSC storage and improve the growth of timber species.

关键词： Pruning intensity Nonstructural carbohydrate Populus alba×P.talassica Seasonal pattern

Solidification behavior of Re-and Ru-containing Ni-based single-crystal superalloys with thermal and metallographic analysis

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Rare Metals 2017年第10期36卷 792-798页

作者： Gang Liu Lin Liu Zhen-Hua Han Guo-jun zhang jun zhang School of Materials Science and Engineering Xi'an University of Technology Xi'an 710048 China State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072 China

To clarify the solidification behavior of Re- and Ru-containing Ni-based single-crystal superalloys, four experimental alloys with varied contents of Re and Ru were investigated by differential scanning calorimetry （DSC） and metallographic techniques. To obtain the - solvus temperatures, the stepwise solution and aging heat treatments were used. DSC analysis shows that Re leads to the increase in freezing range and γ-solvus temperature. On the contrast, Ru only has negligible influence on the freezing range, but leads to the lower γ-solvus temperature. In comparison with Ru, Re leads to more severe segregation and higher eutectic fractions in as-cast microstructures. Furthermore, the castability and phase stability of Ni-based superalloys were analyzed by the results of DSC and metallographic analysis, such as freezing range, critical nucleation temperature, γ-solvus temperature and eutectic fractions. It shows that Re leads to the wider freezing range and lower critical nucleation temperature, indicating the worse castability of Re-con- taining Ni-based single-crystal superalloys.

关键词： Ni-based single-crystal alloys Solidification behavior Metallography Thermal analysis