The Existence and Stability of Synchronizing Solution of Non-Autonomous Equations with Multiple Delays

In this paper, we consider an abstract non-autonomous evolution equation with multiple delays in a Hilbert space H: u'(t) + Au(t) = F(u(t-r1),...,u((t-rn)) + g(t), where A: D(A)?H→H is a positive definite selfadjoint operator, F: Hna → H is a nonlinear mapping, r1,...,rn are nonnegative constants, and g(t)∈ C(□;H) is bounded. Motivated by [1] [2], we obtain the existence and stability of synchronizing solution under some convergence condition. By this result, we provide a general approach for guaranteeing the existence and stability of periodic, quasiperiodic or almost periodic solution of the equation.

Determination of optimal blowing-to-suction flow ratio in mechanized excavation face with wall-mounted swirling ventilation using numerical simulations

Wall-mounted swirling ventilation is a new type of system in mechanized excavation faces with a dust sup-pression performance that is closely related to the blowing-to-suction flow ratio.Physical and simulation models were developed according to the No.C103 mechanized excavation face in the Nahe Coal Mine of the Baise Mining Bureau,Guangxi Province to optimize the blowing-to-suction flow ratio for wall-mounted swirling ventilation.Both the k-εturbulence model and the discrete phase model were utilized to simulate airflow field structures and dust concentration distribution patterns at various blowing-to-suction flow ratios.The results suggest that higher blowing-to-suction flow ratios increase the airflow field disturbance around the working face and weaken the intensity of the axial air curtain.On the other hand,both the intensity of the radial air curtain and the dust suppression effect are enhanced.At a blowing-to-suction flow ratio of 0.8,the wall-mounted swirling ventilation system achieved the most favorable dust suppression performance.Both the total dust and respirable dust had their lowest concentrations with maximum efficiencies of reducing both types at 90.33%and 87.16%,respectively.

湖南大学化学化工实验教学中心的建设与实践

本文以国家级实验教学示范中心阶段性评估为契机,全面总结了2018–2022年间化学国家级实验教学示范中心(湖南大学)在管理制度和安全责任体系建设、教学条件改善、实验教学体系构建、实验课程与教材建设、人才培养成效、教学团队建设和引领示范作用等方面的建设经验,并从示范中心承载能力、实验教学体系优化和实验项目开发、实验数字化建设、教学队伍建设、发挥示范辐射作用等方面制定了下一阶段建设规划,以期更好地支撑我校化学、化工、应化国家一流本科专业的建设,促进化学化工高质量人才培养。

Category of Attractor and Its Application

In this paper, we provide a new approach to study the geometry of attractor. By applying category, we investigate the relationship between attractor and its attraction basin. In a complete metric space, we prove that the categories of attractor and its attraction basin are always equal. Then we apply this result to both autonomous and non-autonomous systems, and obtain a number of corresponding results.

物理化学课程教学中的思政设计——以“理想稀溶液中任一组分的化学势”为例

立德树人是高校教育的根本任务,将思政元素无声融入课堂教学之中,有利于引导学生树立正确的世界观、价值观和人生观,从而成为合格的社会主义接班人。屠呦呦先生是中国第一位荣获诺贝尔自然科学奖的本土科学家。本文以其获得诺贝尔奖的工作“青蒿素高效提取并成功应用于疟疾防治”为例,结合物理化学多组分系统热力学章节中的“分配定律”,改进“理想稀溶液中任一组分的化学势”的教学过程,引导学生充分认识原理对实践的直接指导作用和中华传统文化在解决实际问题中的重要价值,理解科学发现的必然历程以及科学家在不断攀登科学高峰过程中所付出的艰辛和收获,将自己的聪明才智和所学所得应用于祖国的社会主义建设。

新工科背景下湖南大学应用化学专业的改革与建设

探索建立依托化学学科的"新工科"应用化学专业设置并按照"新工科"理念对现有专业进行革命性改造是十分必要的。结合我校2020应用化学专业培养计划修订及教学改革研究的实际情况,通过调整专业培养目标、课程体系、教学内容和教学模式,突出德才兼备人才培养的中心地位,以期在传承本专业腐蚀与防护的特色基础上,进一步满足新材料、新能源、高端制造、节能环保及新一代信息技术等新兴战略产业对人才的需求。还提出了应用化学新工科专业发展的方向。

Skorohod Integral at Vacuum State on Guichardet-Fock Spaces

In this paper, we define expectation of f∈F, i.e. E(f)=f(?), according to Wiener-Ito-Segal isomorphic relation between Guichardet-Fock space F and Wienerspace W. Meanwhile, we derive a formula for the expectation of random Hermite polynomial in Skorohod integral on Guichardet- Fock spaces. In particular, we prove that the anticipative Girsanov identities under the condition E(Hx(δ(x),‖x‖2)),n≥1 on Guichardet-Fock spaces.

Moment Identities for Skorohod Integrals on Guichardet-Fock Spaces

In this paper, we define expectation of f∈E, i.e. E(f)=f(?), accordingto Wiener-Ito-Segal isomorphic relation between Guichardet-Fock space F and Wienerspace W. Meanwhile, we prove a moment identity for the Skorohod integrals aboutvacuum state.

电子购物车推荐效应:基于娱乐产品的田野实验

基于一场包括近13000名消费者并由中国领先的数字阅读平台之一所支持的田野实验,本研究旨在对比电子购物车推荐和主页推荐在娱乐产品领域中的效果。结果表明,与主页推荐相比,电子购物车推荐对消费者下载具有显著的正向影响。此外,当电子购物车中的产品较多时,这种正向影响会减弱;但当消费者更活跃时,这种影响会增强。本研究还发现电子购物车推荐会影响其他产品,使得非推荐产品的下载量增加。我们的发现为研究人员和管理人员提供了新见解,以了解消费者对娱乐产品的电子购物车推荐的反应。

以“人才培养”为中心,全面推进一流专业建设

专业是本科教育的“四梁八柱”。专业建设是一项系统工程,涉及教师、学生以及进行教育教学活动的条件和保障等多方面内容,专业建设的水平和质量直接影响人才培养的质量。本文以湖南大学化学专业为例,分析了专业建设的现状,指明了限制专业发展的问题,同时立足“人才培养”这一中心任务,针对专业建设的短板和不足,从专业建设的软硬件方面提出了改革举措,为一流专业建设提供了借鉴和思路。

Anisotropy of the crystallographic orientation and corrosion performance of high-strength AZ80 Mg alloy

A high-strength AZ80 Mg alloy was prepared through multi-direction forging,thermal extrusion,and peak-aged heat treatment.The microstructure,crystallographic orientation and corrosion performance of extrusion-direction,transverse-direction,and normal-direction specimens were investigated using scanning electron microscopy,electron backscatter diffraction,and atomic force microscopy,respectively.Experimental results showed that crystallographic orientation significantly influenced the corrosion performance of AZ80 Mg alloy.Corrosion rates largely increased with decreased(0001)crystallographic plane intensity,whereas the(10−10)and(2−1−10)crystallographic plane intensities increased.This study showed that the corrosion rates of alloy can be modified to some extent by controlling texture,thereby promoting the applications of high-strength AZ80 Mg alloys in the aerospace and national-defense fields.

The corrosion behaviors of Mg-7Gd-5Y-1Nd-0.5Zr alloy under(NH4)_(2)SO_(4),NaCl and Ca(NO_(3))_(2)salts spray condition

The corrosion behaviors of Mg–7Gd–5Y–1Nd–0.5Zr alloys after T5 treatment under(NH4)_(2)SO_(4),NaCl and Ca(NO_(3))_(2)salt spray condition were investigated by weight loss rates,residual mechanical properties,scanning electron microscope(SEM),X-ray Diffraction(XRD)and potentiodynamic polarization tests.The corrosion degree of Mg–7Gd–5Y–1Nd–0.5Zr alloys in Ca(NO_(3))_(2)salt spray was very shallow by corrosion morphology and the corrosion route was extended along the surface in texture-like shape,while the alloy in NaCl and(NH4)_(2)SO_(4)salt spray were major local corrosion and there were serious corrosion pits on the surface.The weight loss rates in(NH4)_(2)SO_(4),NaCl and Ca(NO_(3))_(2)salt spray was respectively 0.4147,0.1618 and 0.0725 mg/(cm2 d−1).The results of residual mechanical properties indicated that the corrosion order in salts spray of Mg–7Gd–5Y–1Nd–0.5Zr alloys is NH4SO4>NaCl>Ca(NO_(3))_(2),which was consistent with the results of potentiodynamic polarization tests.The type of the salts will play a vital role in the initiation of the corrosion of EW75 alloy when they are used in the atmosphere environments.Inorganic salts with the smaller PH value after dissolution will have a stronger impact on the corrosion of EW75 magnesium alloys.

Pyrolysis of Rice Husk in a Fluidized Bed Reactor:Evaluate the Characteristics of Fractional Bio-Oil and Particulate Emission of Carbonaceous Aerosol(CA)

Bio-oil production via pyrolysis is one of promising technologies for renewable energy production from bio-wastes.However,the complicated biooil is still a challenge for high-valued application and during biomass pyrolysis,the emission of non-cleaned aerosol,the potential emission,namely carbonaceous aerosol(CA)increased the difficulty of the commercial promotion.In this study,Rice husk pyrolysis was performed in a semi-continuous fluidized bed reactor coupled with fractional condensers.The effects of pyrolysis and condensation temperature on the properties of bio-oil and emission of CAwere investigated systemically.Results indicated that the in-situ separation of vapors was accomplished via condensers of different temperatures(85℃and−10℃).The bio-oil with different physiochemical properties were obtained in the high content of phenols and lower acids of BO1 and high content of acids and better liquidity.The size distribution of CA was found primarily classified as sub-micrometer grade particles,which have a diameter of less than 1.1μm.In particular,CA existed in three representative forms:bead,granular aggregate,and liquidoid.The results of light absorption of total organic carbon(TOC)and non-volatile organic carbon(NVOC)indicated that the absorption per mass increased in the single temperature with the decrement of wavelength and it improved as the pyrolysis temperature increased at the specified wavelength.The absorption per mass was to maximum value(3.7 m^(2)/g)at 360 nm wavelength and 600℃.TOC demonstrated a strong light absorption and a wide spectral range dependence(AAE:5.08-10.05)which enhanced the light absorption in the ultra-violet and low-visible regions.

Dynamic precipitation during multi-axial forging of an Mg-7Gd-5Y-1Nd-0.5Zr alloy

The dynamic precipitation behavior during multi-axial forging in an Mg-7Gd-5Y-1Nd-0.5Zr alloy has been investigated and compared with that in static precipitation treatment. The results indicated that dynamic precipitation does occur during multi-axial forging. The dynamic precipitate can be deduced as β phase with face-centered cubic crystal structure (a = 2.22 nm). Most of the β precipitates locate at the dynamic recrystallization grain boundaries. The morphology and orientation relationship is different from that of the β phase formed in the static precipitation treated alloys, although the crystal structure is the same. The precipitation temperature of β phase during MAF is higher than that in the static precipitation treatment.

Significance of VEGF and NF-κB Expression in Thyroid Carcinoma

OBJECTIVE To investigate the significance of vascular endothelial growth factor (VEGF) and nuclear factor-kappaB (NF-κB) expression in thyroid carcinoma. METHODS The expression of NF-κB and VEGF was determined by im- munohistochemistry in formalin-fixed and paraffin-embedded specimens obtained from 10 normal thyroid tissues (NT), 12 cases of thyroid adeno- ma (TA) and 68 cases of thyroid carcinoma (TC).Differences in expres- sion between NT, TA and TC were statistically analyzed. In addition, in cases of TC, the relationship of NF-κB and VEGF expression with various clinicopathological factors, including histological typing, clinical staging and lymph node metastasis, as well as the correlation between N F - κ B and VEGF expression was examined. RESULTS In contrast to the negative immunoreactivity for VEGF in NT, there was a significantly higher positive incidence (PI) in TA (41.7%, P= 0.040) and TC (75.0%, P<0.001), and a significant difference between TA and TC (P=0.036). Immunoreactivity for NF-κB in NT was negative and significantly higher in TC (63.2%, P<0.001),but not in TA (16.7%, P= 0.481). However the PI difference between TA and TC (P=0.003) was significant. Between the histological types of TC, a significantly higher PI was found in undifferentiated thyroid carcinoma (UTC),namely,100% for VEGF and 90.0% for NF-κB. We also found significant positive relation- ships of VEGF and N F - κ B expression with the clinical stage and lymph node metastasis. Furthermore, a significant positive correlation between VEGF and NF-κB expression in TC was observed. CONCLUSION Our data showed that the expression of VEGF and NF- ΚB/P65 was greater in TC and UTC, and documented their significant positive correlations with the clinical stage and lymph node metastasis in TC. In addition there was a significant positive relationship between their expression, suggesting that they have important roles in TC and that they may be potential targets for gene therapy in TC patients.

Formation and growth of precipitates in a Mg-7Gd-5Y-1Nd-2Zn-0.5Zr alloy aged at 200℃

Crystal structures,growth characteristics,and transformation of the precipitates in a Mg-7Gd-5Y-1Nd-2Zn-0.5Zr(wt.%)alloy aged at 200℃for various durations were investigated using transmission electron microscopy(TEM)and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM).A detailed Mg-Gd type precipitation sequence for Mg-Gd-Y-Nd-Zn alloys was proposed as follows:supersaturated solid solution→solute clusters→zigzag GP zones+β''(I)→β'→β'+protrusions/joints→pre-β_(1)→β_(1)→β.Solute clusters formed in the early stage of aging consisted of one or more rare-earth(RE)/Zn-rich atomic columns with different configura-tions.RE/Zn-rich solute clusters grew into zigzag GP zones andβ''(I)as aging time extending.The paired-zigzag GP zones might grow up to beβ'precipitates directly.In the peak-and plat-aging stages,the number of solute clusters in the matrix decreased until they disappeared,and most existed as zigzag arrays and super hexagons.Protrusions formed at the end ofβ'at an angle of 120°,then grew into joints when two differentβ'variants encountered together.Protrusions/joints comprise zigzag arrays,super-hexagons,β'F,β''(II),β_(T),and hybrid structures rich in solute atoms,and act as catalysts for the growth of theβ'variants.Largerβ'grow by joints consumption while smallerβ'precipitates dissolve to form joints.β_(1)precipitates essentially evolve from pre-β_(1)precipitates,with four-point diamond structures formed by RE/Zn atomic substitution and atomic migration based on the originalα-Mg structure.

Theoretical research on terahertz wave generation from planar waveguide by optimized cascaded difference frequency generation

A novel scheme for high-efficiency terahertz(THz)wave generation based on optimized cascaded difference frequency generation(OCDFG)with planar waveguide is presented.The phase mismatches of each-order cascaded difference frequency generation(CDFG)are modulated by changing the thickness of the waveguide,resulting in a decrement of phase mismatches in cascaded Stokes processes and an increment of phase mismatches in cascaded anti-Stokes processes simultaneously.The modulated phase mismatches enhance the cascaded Stokes processes and suppress the cascaded anti-Stokes processes simultaneously,yielding energy conversion efficiencies over 25%from optical wave to THz wave at 100 K.

Pullback Exponential Attractors for Nonautonomous Reaction Diffusion Equations in H₀<sup style="margin-left:-6px;">1</sup>

Under the assumption that ?g(t) is translation bounded in , and using the method developed in [3], we prove the existence of pullback exponential attractors in ?for nonlinear reaction diffusion equation with polynomial growth nonlinearity(?is arbitrary).

DEA Models for the Efficiency Evaluation of System Composed of Parallel Subsystems

The perspective of internal structure of the decision making units (DMUs) was considered as the “black box” when employing data envelopment analysis (DEA) models. However, in the actual world there are always some DMUs that are composed of several sub-units or subsystems, each utilizes the same inputs to generate same outputs. Numerous instances can be listed, such as a firm with a few of plants. In this paper we present models that evaluated the efficiency of DMU which is comprised of same several parallel subsystems, the foremost contribution of our work is that we take the different importance of the subsystems into account in the model, which can be obviously distinguished to the existing DEA model. Secondly, since the alternative optimal multipliers may emerge in the model, the efficiency of each subsystem may be non-unique and we simultaneously develop models of efficiency decomposition for each subsystem. At last a case of technological innovation activities of each province in China is used as an example to state the models.

On Two Birkhoff-Type Interpolations with First- and Second-Order Derivative

In this paper, we consider two interpolations of Birkhoff-type with integer-order derivative. The Birkhoff interpolation is related with collocation method for the corresponding initial or boundary value problems of differential equations. The solvability of the interpolation problems is proved. For Gauss-type interpolating points, error of interpolation approximation is deduced. Also, we give efficient algorithms to implement the concerned interpolations.