高速铁路隧道衬砌裂缝气动荷载激化效应

研究目的:高速铁路隧道掉块频发可能引发严重的经济损失甚至人员伤亡。高速列车气动荷载在裂缝内的激化效应可能是导致裂缝拓展并最终形成掉块的重要原因。为防止高速铁路隧道掉块事故发生,加强隧道病害治理,应对衬砌裂缝气动荷载的激化效应展开针对性研究。本文基于Fluent软件采用有限体积法(FVM)和Pressure-Based求解器,考虑空气可压缩性,采用非稳态粘性k-ε湍流模型对裂缝空间内的气动压力进行模拟,利用该模型讨论环向、斜向、纵向裂缝气动荷载的时空特征,分析气动压力的频谱特征,并对比裂纹长度、宽度、深度及车速对裂缝面气动荷载的影响。研究结论:(1)压力波进入环向裂缝腔内具有瞬时性,而进入斜向与纵向裂缝腔内具有过程性;(2)环向裂缝压力峰值最大,为输入压力的5.32倍;斜向、纵向裂缝压力峰值分别仅为环向裂缝相应值的79.5%与64.9%;(3)环向裂缝气动压力PSD平均值是纵向裂缝和斜向裂缝相应值的4.04倍和1.54倍;(4)裂纹长度、宽度对裂缝面压力峰值的影响有限,裂纹深度与压力峰值满足线性函数关系,车速与压力峰值满足幂指数为2.3033的幂函数关系;(5)本研究成果可为高铁隧道的设计、隧道内裂缝的评估和修复提供参考。

胎次-激化双重效应:中国生育政策与出生性别比关系的理论构建与实证研究

通过构建"胎次-激化双重效应"理论模型,解读生育政策与出生性别比关联的潜在机制,并利用宏观数据予以检验。政策与出生性别比的失衡存在直接和间接双重关系;生育政策的刚性制约和一孩半生育政策赋予胎次和激化效应特殊含义:(1)一孩政策地区低胎的出生性别比偏高、一孩半政策地区二胎及以上胎次的出生性别比极度失衡,显现"激化效应";(2)政策的多样性使部分低位女胎与男胎一样受欢迎,使一孩半政策及二孩政策地区低胎的出生性别比趋于正常,产生"胎次效应"。可见,政策越强,低位和高位女胎都不受重视,均会遭遇人工流产;相反,在相对宽松的政策环境下,低位女胎所受的歧视程度相对减弱。

The analysis on IP signals in TEM response based on SVD

During transient electromagnetic method （TEM） exploration of a copper mine, we detected the late-channel TEM signal reversal phenomenon （a voltage change from positive to negative） caused by the influence of the induced polarization （IP） effect, which affects the depth and precision of the TEM detection. The conventional inversion method is inefficient because it is difficult to process the data. In this paper, the Cole-Cole model is adopted to analyze the effect of Dc resistivity, chargeability, time constant, and frequency exponent on the TEM response in an homogeneous half space model. Singular Value Decomposition （SVD） is used to invert the measured TEM data, and the Dc resistivity, chargeability, time constant and frequency exponent were extracted from the measured TEM data in the mine area. The extracted parameters are used for interpreting the detection result as a supplement. This reveals why the TEM data acquired in the area has a low resolution. It was found that the DC resistivity and time constant do not significantly change the results, however, the chargeability and frequency exponent have a significant effect. Because of these influences, the SVD method is more accurate than the conventional method in the apparent resistivity profile. The area of the copper mine is confined accurately based on the SVD inverted data. The conclusion has been verified by drill and is identical to the practical geological situation.

财政压力、地方政府行为与环境污染

地方政府是生态环境治理的关键主体,财政压力以地方政府行为作为传导变量,对环境污染及其治理效果有深刻影响。实证检验地方政府行为的促污和治污效应对财政压力冲击的响应。结果表明:激励生产型地方政府行为促进污染增加,在财政压力下促进污染增加效应的激化,即压力越大越污染。环境治理型地方政府行为中的环境保护支出对污染治理有效,财政压力对其治污效应有提升作用;排污费征收不治污、反促污,财政高压使其促污效应强化。在财政增支减收、压力不断攀升的背景下,可从治理体制性财政压力诱因、强化对地方政府行为监督和约束以及优化治理工具提升环境治理绩效等方面来平抑财政压力通过地方政府行为引发的环境污染加剧。

Effect of Estrogen and Antiestrogen on Chemotherapeutic Sensitivity of Endometrial Carcinoma Cell Line

Objective: To study the effect of estrogen and tamoxifen on chemotherapeutic sensitivity in ER(+) endometrial carcinoma cells.Methods: DNA fragmentation as the criteria for apoptotic cell death was used to evaluate the value of estrogen, tamoxifen and adriamycin in ER(+) endometrial carcinoma cells. DNA fragmentation was measured with the cell death ELISA.Results: Adriamycin and tamoxifen could induce apoptosis in ER(+) endometrial carcinoma cell. The cell apoptosis level was decreased with the increasing of 17-β-estradiol concentration (P<0.001) and was inversely proportional to 17-β-estradiol concentration (IgM) (P<0.01). The cell apoptosis level was increased with the increasing of tamoxifen concentration (P<0.01) and was also directly proportional to tamoxifen concentration (IgM). Furthermore, the cell apoptosis level was increased significantly after treated with both tamoxifen and adriamycin.Conclusion: Estrogen may block apoptosis induced by adriamycin in ER(+) endometrial carcinoma cell. Tamoxifen can increase the sensitivity of endometrial carcinoma cell to adriamycin. Tamoxifen combined with chemotherapeutic drug may be of significant therapeutic benefit in ER(+) endometrial carcinoma. Key words endometrial carcinoma - estrogen - tamoxifen - adriamycin - cell apoptosis

Energies and Transition Rates of Low-Lying Excited States for Beryllium

Low lying excited states of beryllium are calculated with multiconfiguration interaction method. The relativisitic corrections and mass polarization are included. The oscillator strength and radiation rates are also calculated. Our results are in good agreement with other theoretical data.

Cooperative effect of surface alloying and laser texturing on tribological performance of lubricated surfaces

The cooperative effect of laser surface texturing(LST) and double glow plasma surface alloying on tribological performance of lubricated sliding contacts was investigated.A Nd:YAG laser was used to generate microdimples on steel surfaces. Dimples with the diameter of 150μm and the depth of 30-35μm distributed circumferentially on the disc surface.The alloying element Cr was sputtered to the laser texturing steel surface by double glow plasma technique.A deep diffusion layer with a thickness of 30μm and a high hardness of HV900 was formed in this alloy.Tribological experiments of three types of samples(smooth,texturing and texturing+alloying) were conducted with a ring-on-disc tribometer to simulate the face seal.It is found that,in comparison with smooth steel surfaces,the laser texturing samples significantly reduce the friction coefficient.Moreover,the lower wear rate of the sample treated with the two surface techniques is observed.

Exchange Bias Effect in Phase Separated La0.33Pr0.34Ca0.33MnO3 Thin Films

Exchange bias effect is observed in the phase separated La0.33Pr0.34Ca0.33MnO3 thin films. High exchange bias field of about 1 kOe is achieved at 4 K. The exchange bias effect in La0.33Pr0.34Ca0.33MnO3 thin films might originate from the intrinsic phase separation of the La0.33Pr0.34Ca0.33MnO3 or surface effect. The dependence of exchange bias effect on temperature, cooling field, and thickness is also investigated. This work would open an avenue to the application in the magnetic memory devices based on the phase separated manganites.

Effects of Au nanoparticle size and metal-support interaction on plasmon-induced photocatalytic water oxidation

Plasmonic photocatalysis with tunable light absorption has aroused significant attention in so-lar-to-chemical energy conversion.However,the energy conversion efficiency of plasmonic photo-catalysts is impeded by ineffective charge separation and the lack of highly active sites for redox reactions.In this work,the Au nanoparticle size and Au-TiO2 interaction of the Au/TiO2 plasmonic photocatalyst were adjusted simultaneously using a post-calcination treatment.The visi-ble-ight-induced water oxidation activity exhibited a volcano-like relationship with the calcination temperature;the treated photocatalyst at 600°C manifested the highest activity.Characterization with UV-visible spectra,XRD,SEM,and XPS revealed that the effect of the Au nanoparticle size and Au-TiO2 interaction were both responsible for the increase in plasmon-induced water oxidation activity.

Interfacial Shear Stress of Stratified Flow in a Horizontal Pipe

Experimental data are presented for the void fraction and the shear stresses of stratified gas-liquid flow in a pipe. A new technique was used to measure the interface shear stress. The interfacial shear stress was determined by using two methods: a momentum balance of gas and an extrapolation of the Reynolds shear stress profile at the gas-liquid interface. A new formula , relating to the interfacial friction factor with the void fraction and superficial gas Reynold number, was developed to predict the interface shear stress . The predicted values are in good agreement with experimental data.

Toxic Dinoflagellate Alexandrium tamarense Induces Oxidative Stress and Apoptosis in Hepatopancreas of Shrimp(Fenneropenaeus chinensis)

This study investigated the inductive effect ofAlexandrium tamarense, a toxic dinoflagellate producing paralytic shell- fish poison, on oxidative stress and apoptosis in hepatopancreas of Chinese shrimp, Fenneropenaeus chinensis. The individuals of E chinensis were exposed to 200 and 1000 cells mL-1 of A. tamarense with their superoxide dismutase （SOD）, glutathione S-transferase （GST） activities, malonyldialdehyde （MDA） concentration, and caspase gene （FcCasp） expression in hepatopancreas determined at 12, 24, 48, 72 and 96 h. In addition, apoptosis in hepatopancreas of E chinensis at 96 h after exposure was determined through terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling （TUNEL） assay. The hepatopancreatic SOD and GST activities of F. chinensis exposed to 1000 cells mL-1 ofA. tamarense showed a bell-shaped response to exposure time. The hepatopancreatic MDA concentration ofF. chinensis exposed to 1000 cellsmL-1 ofA. tamarense increased gradually from 48 to 96h, and such a trend corresponded to the decrease of GST activity. The hepatopancreatic FcCasp transcript abundance of F. chinensis exposed to 1000 cells mL-1 ofA. tamarense was positively and linearly correlated to MDA concentration. Results of TUNEL assay showed that exposure to 1000 cells mL-1 of A. tamarense induced apoptosis in the hepatopancreas of E chinensis. Our study revealed that A. tamarense exposure influenced the antioxidative status ofF. chinensis and caused lipid peroxidation and apoptosis in the hepatopancreas of shrimp.

Stark Effect Dependence on Hydrogenic Impurities in GaAs Parabolic Quantum-Well Wires

The ground-state and lowest excited-state binding energies of a hydrogenic impurity in GaAs parabolic quantum-well wires （Q WWs） subjected to external electric and magnetic fields are investigated using the finite-difference method within the quasi-one-dimensional effective potential model. We define an effective radius Pen of a cylindrical QWW, which can describe the strength of the lateral confinement. For the ground state, the position of the largest probability density of electron in x-y plane is located at a point, while for the lowest excited state, is located on a circularity whose radius is Pen. The point and circularity are pushed along the left haft of the center axis of the quantum-well wire by the electric field dire ted along the right half. When an impurity is located at the point or within the circularity, the ground-state or lowest excited-state binding energies are the largest; when the impurity is apart from the point or circularity, the ground-state or lowest excited-state binding energies start to decrease.

Effects of Different Acupuncture Stimulations on NO Content in Acupoint Areas

Objective:To study the effects of different acupuncture stimulation on nitric oxide(NO) content in acupoint areas.Methods:The experiment was performed in 47 healthy volunteers providing informed consents.Both males and females were included in each group:11 cases in electro-acupuncture group,13 cases in manual-acupuncture group,16 cases in warm-moxibustion group,and 7 cases in control group.Stimulations were given at Jianshi(PC 5) of the Pericardium Meridian and Chengshan(BL 57) of the Bladder Meridian with manual-acupuncture,electro-acupuncture and warm-moxibustion respectively.NO was collected from Ximen(PC 4) and Chengjin(BL 56) areas on the ipsilateral meridians,and the content was detected.Results:The content of NO in the warm-moxibustion group was higher than that in the electro-acupuncture group,the content in electro-acupuncture group was higher than that in the manual acupuncture group(P<0.05) . Conclusion:All the three stimulations can raise NO levels on acupoint areas significantly,and the effect moxibustion is superior to that of electro-acupuncture and manual acupuncture.

Laser-enhanced thermal effect of moderate intensity focused ultrasound on bio-tissues

For avoiding extra-damage to healthy tissues surrounding the focal point during high intensity focused ultrasound(HIFU) treatment in medical therapy, to reduce the ultrasonic intensity outside the focal point is expected. Thus, the heating processes induced by moderate intensity focused ultrasound(MIFU) and enhanced by combined irradiation of laser pulses for bio-tissues are studied in details. For fresh bio-tissues, the enhanced thermal effects by pulsed laser combined with MIFU irradiation are observed experimentally. To explore the mechanisms of these effects, several tissue-mimicking materials composed of agar mixed with graphite powders are prepared and studied for comparison, but the laser-enhanced thermal effects in these mimicking materials are much less than that in the fresh bio-tissues. Therefore, it is suggested that the laser-enhanced thermal effects may be mainly attributed to bio-activities and related photo-bio-chemical effects of fresh tissues.