TP55节段拼装架桥机纵移过跨墩顶块稳定性分析与控制

芜湖长江公路二桥引桥采用全悬挂预制节段梁施工工艺,墩顶块为全预制。对称悬拼结构墩顶块架桥机可以直接安装,考虑到架桥机支腿的站位,一般情况下全悬挂结构预制墩顶块不宜直接安装。本桥桥址位于长江漫滩及平原陆地,线路长,地形多变,采用非架桥机安装设备安装墩顶块很难实现,也不利于架桥机安装标准化施工。因此本桥墩顶块需架桥机直接安装,且架桥机主承重支腿需站位于已安装好的墩顶块上。本桥墩顶块为两榀预制箱梁通过临时预应力串成一榀,串成一榀箱梁的墩顶块的长度超过墩柱的长度,解决架桥机纵移过跨产生的水平推力及附加弯矩是本桥施工的一项重点和难点。本文将针对芜湖长江公路二桥节段梁墩顶块安装这一特殊工况,系统的分析架桥机纵移过跨墩顶块的稳定性,并通过优化理论分析数据,总结出控制纵移水平推力的方法。

一种全自动酶免分析仪移液过程评估新方法

为了提高全自动酶免分析仪微量移液系统的可靠性,对移液过程压力监控曲线建立了基于灰色聚类分析的定性评估模型,对正常移液过程以及气泡、堵针、样本量不足等异常移液过程进行准确判定及报警。首先,利用差分法求取正常移液过程压力一阶导数曲线,以此作为参照建立移液过程的指标模型,并采用基于中心点三角白化权函数对多样性的评价指标进行灰量白化;然后,按照聚类指标将移液过程进行灰色聚类,计算不同移液过程所有指标的综合聚类效果,并以聚类类型为依据对移液过程进行定性评估。在此基础上,对压力监控一阶导数曲线进行灰色动态平滑滤波,消除基线漂移和随机噪声。最后搭建了微量移液实验系统,并对任取的11次移液过程进行定性综合评估。实验结果表明,该定性综合评估方法能够对正常及各种异常移液过程进行准确判定,并且给出问题类型。

天线罩刚度强度及稳定性分析

本文对052天线罩的力学模型的建立、计算方法、荷载处理、边界条件处理以及计算结果进行了系统介绍,对工程应用具有指导意义。

Semi-analytical solution for mechanical analysis of tunnels crossing strike-slip fault zone considering nonuniform fault displacement and uncertain fault plane position

The tunnel subjected to strike-slip fault dislocation exhibits severe and catastrophic damage.The existing analysis models frequently assume uniform fault displacement and fixed fault plane position.In contrast,post-earthquake observations indicate that the displacement near the fault zone is typically nonuniform,and the fault plane position is uncertain.In this study,we first established a series of improved governing equations to analyze the mechanical response of tunnels under strike-slip fault dislocation.The proposed methodology incorporated key factors such as nonuniform fault displacement and uncertain fault plane position into the governing equations,thereby significantly enhancing the applicability range and accuracy of the model.In contrast to previous analytical models,the maximum computational error has decreased from 57.1%to 1.1%.Subsequently,we conducted a rigorous validation of the proposed methodology by undertaking a comparative analysis with a 3D finite element numerical model,and the results from both approaches exhibited a high degree of qualitative and quantitative agreement with a maximum error of 9.9%.Finally,the proposed methodology was utilized to perform a parametric analysis to explore the effects of various parameters,such as fault displacement,fault zone width,fault zone strength,the ratio of maximum fault displacement of the hanging wall to the footwall,and fault plane position,on the response of tunnels subjected to strike-slip fault dislocation.The findings indicate a progressive increase in the peak internal forces of the tunnel with the rise in fault displacement and fault zone strength.Conversely,an augmentation in fault zone width is found to contribute to a decrease in the peak internal forces.For example,for a fault zone width of 10 m,the peak values of bending moment,shear force,and axial force are approximately 46.9%,102.4%,and 28.7% higher,respectively,compared to those observed for a fault zone width of 50 m.Furthermore,the position of the peak internal forces is influenced by variations in the ratio of maximum fault displacement of the hanging wall to footwall and the fault plane location,while the peak values of shear force and axial force always align with the fault plane.The maximum peak internal forces are observed when the footwall exclusively bears the entirety of the fault displacement,corresponding to a ratio of 0:1.The peak values of bending moment,shear force,and axial force for the ratio of 0:1 amount to approximately 123.8%,148.6%,and 111.1% of those for the ratio of 0.5:0.5,respectively.

Synchrotron-Radiation Photoemission Study of Growth and Stability of Au Clusters on Rutile TiO2（110）-1×1

The growth and thermal stability of Au clusters on a partially-reduced rutile TiO2 （110）-1 × 1 surface were investigated by high-resolution photoelectron spectroscopy using synchrotron- radiation-light. The valence-band photoelectron spectroscopy results demonstrate that the Ti^3＋3d feature attenuates quickly with the initial deposition of Au clusters, implying that Au clusters nucleate at the oxygen vacancy sites. The Au4f core-level photoelectron spectroscopy results directly prove the existence of charge transfer from oxygen vacancies to Au clusters. The thermal stability of Au clusters on the partially-reduced and stoichiometric TiO2（110） surfaces was also comparatively investigated by the annealing experiments. With the same film thickness, Au clusters are more thermally stable on the partially-reduced TiO2（110） surface than on the stoichiometric TiO2（110） surface. Meanwhile, large Au nanoparticles are more thermally stable than fine Au nanoparticles.

Weighted-elastic-wave interferometric imaging of microseismic source location

Knowledge of the locations of seismic sources is critical for microseismic monitoring. Time-window-based elastic wave interferometric imaging and weighted- elastic-wave （WEW） interferometric imaging are proposed and used to locate modeled microseismic sources. The proposed method improves the precision and eliminates artifacts in location profiles. Numerical experiments based on a horizontally layered isotropic medium have shown that the method offers the following advantages： It can deal with Iow-SNR microseismic data with velocity perturbations as well as relatively sparse receivers and still maintain relatively high precision despite the errors in the velocity model. Furthermore, it is more efficient than conventional traveltime inversion methods because interferometric imaging does not require traveltime picking. Numerical results using a 2D fault model have also suggested that the weighted-elastic-wave interferometric imaging can locate multiple sources with higher location precision than the time-reverse imaging method.

Enhancing the photocatalytic activity and photostability of zinc oxide nanorod arrays via graphitic carbon mediation

Low optical absorption and photocorrosion are two crucial issues limiting the practical applications of zinc oxide(ZnO)-based photocatalysts.In this paper,we report the fabrication of graphitic-carbon-mediated ZnO nanorod arrays(NRAs)with enhanced photocatalytic activity and photostability for CO2 reduction under visible light irradiation.ZnO NRA/C-x(x=005,01,02,and 03)nanohybrids are prepared by calcining pre-synthesized ZnO NRAs with different amounts of glucose(0.05,0.1,0.2,and 0.3 g)as a carbon source via a hydrothermal method.X-ray photoelectron spectroscopy reveals that the obtained ZnO NRA/C-x nanohybrids are imparted with the effects of both carbon doping and carbon coating,as evidenced by the detected C-O-Zn bond and the C-C,C-O and C=O bonds,respectively.While the basic structure of ZnO remains unchanged,the UV-Vis absorption spectra show increased absorbance owing to the carbon doping effect in the ZnO NRA/C-x nanohybrids.The photoluminescence(PL)intensities of ZnO NRA/C-x nanohybrids are lower than that of bare ZnO NRA,indicating that the graphitic carbon layer coated on the surface of the ZnO NRA significantly enhances the charge carrier separation and transport,which in turn enhances the photoelectrochemical property and photocatalytic activity of the ZnO NRA/C-x nanohybrids for CO2 reduction.More importantly,a long-term reaction of photocatalytic CO2 reduction demonstrates that the photostability of ZnO NRA/C-x nanohybrids is significantly increased in comparison with the bare ZnO NRA.

Study for reasonable value of friction coefficient between main cable and saddle

The value of friction coefficient between the main cable and saddle, relates to not only the anti-slippage stability of three-tower suspension bridge, but also the reasonable stiffness of the middle tower and the magnitude of rigidity of the whole bridge. First, the paper does some comparative studies about the relevant provisions of international norms, and then, summarizes the relevant load test results both at home and abroad. Finally, the paper draws the appropriate anti-slippage safety factor for the most unfavorable load in accordance with international load standards, and discusses the rationality and feasibility of the friction coefficient of 0.2 between main cable and saddle.

Telomerase activity in colorectal cancer,prognostic factor and implications in the microsatellite instability pathway

AIM： To determine whether the telomerase activity is related to the Microsatellite instability （MSI） genetic pathway and whether it means a difference in the survival.METHODS： The population consisted of 97 colorectal cancer patients. MSI determination was performed in accordance with the NCI criteria using PCR and Genescan. Telomerase activity was determined by the TRAP-assay, an ELISA procedure based on the amplification of telomeric repeat sequences.RESULTS： 6.2% showed high MSI （MSI-H）, 10.3% showed low MSI （MSI-L） and 83.5% did not show this alteration （MSS）. Positive telomerase activity was detected in 92.8% of the patients. 83.3% of MSI-H tumors showed positive telomerase against 93.8% of MSS tumors. In the overall survival analysis the absence of telomerase activity conferred a better prognosis.CONCLUSION： Previous works have shown that tumors which develop via the MSI pathway present a better prognosis. No link between telomerase activity and MSl status is observed, although sample sizes are small. Patients with telomerase negative tumors had better overall survival than patients with telomerase positive tumors.

Stability of Disclinations in Nematic Liquid Crystals

In the light of C-mapping method and topological current theory, the stability of disclinations around a spherical particle in nematic liquid crystals is studied. We consider two different defect structures around a spherical particle： disclination ring and point defect at the north or south pole of the particle. We calculate the free energy of these different defects in the elastic theory. It is pointed out that the total Frank free energy density can be divided into two parts. One is the distorted energy density of director field around the disclinations. The other is the free energy density of disclinations themselves, which is shown to be concentrated at the defect and to be topologically quantized in the unit of （k - k24）π/2. It is shown that in the presence of saddle-splay elasticity a dipole （radial and hyperbolic hedgehog） configuration that accompanies a particle with strong homeotropic anchoring takes the structure of a small disclination ring, not a point defect.

Monitoring and stability analysis of slope slip of a landfill with multiple intermediate covering layers

A field monitoring program was carried out to record the slope failure process of a landfill with multiple intermediate covering layers.The monitored items include the leachate level,the surface horizontal displacement and the deep lateral displacement.Based on the monitoring data,analysis was carried out to verify the stability control effects of leachate drainage on the top layer,leachate drainage in different layers,and near-slope leachate drainage.The results show that the maximum slip area is 34 760 m 2 and the average surface horizontal displacement of the 10th platform is 1.77 m.Dumping near the slope is the main reason for the instability.The closer to the dumping area,the greater the degree of slip and the more significantly the leachate level rises.Affected by the intermediate covering layers,the failure mode is the local sliding inside the landfill,and the effect of near-slope leachate drainage on the stability control is obvious.

Verified Solution for a Statically Determinate Truss Structure with Uncertain Node Locations

We consider a statically determinate structural truss problem where all of the physical model parameters are uncertain： not just the material values and applied loads, but also the positions of the nodes are assumed to be inexact but bounded and are represented by intervals. Such uncertainty may typically arise from imprecision during the process of manufacturing or construction, or round-off errors. In this case the application of the finite element method results in a system of linear equations with numerous interval parameters which cannot be solved conventionally. Applying a suitable variable substitution, an iteration method for the solution of a parametric system of linear equations is firstly employed to obtain initial bounds on the node displacements. Thereafter, an interval tightening （pruning） technique is applied, firstly on the element forces and secondly on the node displacements, in order to obtain tight guaranteed enclosures for the interval solutions for the forces and displacements.

Scalable and Identifier/Locator-Splitting Routing Protocol for Mobile Ad Hoc Networks

In the traditional Intemet Protocol （IP） architecture, there is an overload of IP sermntic problems. Existing solutions focused mainly on the infrastructure for the fixed network, and there is a lack of support for Mobile Ad Hoc Networks （MANETs）. To improve scalability, a routing protocol for MANETs is presented based on a locator named Tree-structure Locator Distance Vector （TLDV）. The hard core of this routing method is the identifier/locator split by the Distributed Hash Table （DHT） method, which provides a scalable routing service. The node locator indicates its relative location in the network and should be updated whenever topology changes, kocator space ks organized as a tree-structure, and the basic routing operation of the TLDV protocol is presented. TLDV protocol is compared to some classical routing protocols for MANETs on the NS2 platform Results show that TLDV has better scalability. Key words：

Multi-objective optimization of active steering system with force and displacement coupled control

A novel active steering system with force and displacement coupled control(the novel AFS system) was introduced,which has functions of both the active steering and electric power steering.Based on the model of the novel AFS system and the vehicle three-degree of freedom system,the concept and quantitative formulas of the novel AFS system steering performance were proposed.The steering road feel and steering portability were set as the optimizing targets with the steering stability and steering portability as the constraint conditions.According to the features of constrained optimization of multi-variable function,a multi-variable genetic algorithm for the system parameter optimization was designed.The simulation results show that based on parametric optimization of the multi-objective genetic algorithm,the novel AFS system can improve the steering road feel,steering portability and steering stability,thus the optimization method can provide a theoretical basis for the design and optimization of the novel AFS system.

Three-time rapid transfer alignment method of SINS/GPS navigation system of high-speed marine missile

The transfer alignment of SINS/GPS navigation system of a high-speed marine missile was investigated. With the help of the big acceleration of a high-speed missile, the transfer alignment was changed into a three-time alignment. The azimuth alignment was coarsely finished in 10s in the first time alignment, the horizontal alignment was accurately and rapidly finished in the second time alignment, and the azimuth alignment was accurately finished in the third time alignment. Because the second time alignment and the third time alignment were finished by GPS after the missile was launched, the horizontal alignment and the second azimuth alignment got rid of the influence of the warship body flexibility deforming. The precision and rapidity of the horizontal alignment were prominently increased due to the vertical launch of the marine missile with the big acceleration. Simulation verifies the effectiveness of the proposed alignment method.

MINING INDUCED INFLUENCE ON THE ROADWAYS IN WEAK SURROUNDING ROCK AND ITS CONTROLLING MEASURES

The application of destressing method can change the distribution patterns of the stress field in the weak rock surrounding openings. locate the openings in the zone of low stress level, thus improve their loading and maintaining conditions. Such method is considered as a new way of opening maintenance in weak rock and has caused extensive interests in mining industry both at home and abroad. The results of theoretic research and lab experiments of utilizing top-destressing trough to maintain the opening affected by mining activities in weak rock, as well as its practical application in a coal mine are introduced in this paper. The research results indicate that the deformation and floor heaving of the opening in weak rock can be effectively controlled, and long-term stability of the opening can be realized by applying destressing method as long as the destressing plan and concerned parameters are carefully determined.

Analysis on Dam-Breaking Mode of Tangjiashan Barrier Dam in Beichuan County

Tangjiashan landslide is a typical high-speed consequent landslide of medium-steep dip angle. This landslide triggered by earthquake took place in about semi-minute. The relative sliding displacement is 900 meters, so average sliding speed is about 30 meters per second. The longitudinal length of barrier dam which is formed by high-speed landslide along river is 803.4 meters; and maximum width crossing river is 611.8 meters. And its volume is estimated about 20.37 million steres. Through detailed geological investigation of the barrier dam, together with early geological information before earthquake, geological structures of the barrier dam and its stability of upstream and downstream slopes are studied when water level reaches different elevations in condition of continual after shocks with seismic intensity of 7 or 8 Richter scale. On this basis, dam-breaking mode of barrier dam is discussed deeply. Thereby, analytic results provide significant guidance and advices to front headquarters of Tangjiashan barrier dam, so that some proper engineering measures can be implemented and flood discharge can be carried out well.

Stability analyses of bleeder pillars in longwall mines by displacement-discontinuity method

Caving in coal mines releases significant amounts of dust and gas. This is exhausted from the mine by forcing the air to travel through the caved zones into a set of roadways known as bleeders. These bleeder entries are operated for the life of the mine, and therefore, they have to be kept in stable condition. Caving operations in coal mines are associated with Iongwall mines and complete pillar extraction. The pillars adjoining the caved zone sometimes show rib failures, posing a hazard for mine personnel travelling through the entry. In this paper, we present the results from analyses of bleeder pillars that are near the caved zones and are susceptible to damage because of the transfer of load during the caving process. In this study, bleeder pillars were simulated in a displacement discontinuity program. Results showed that the vertical stresses on bleeder pillars increased while the safety factor of bleeder pillar decreased during the caving process; however, when the caved zone completely consolidated, both the stresses and safety factor did not change for the remaining extraction. When similar extraction was performed at deeoer denths, vertical stress on pillars increased significantly_

A simple theoretical approach for analysis of slide-toe-toppling failure

A prevalent kind of failure of rock slopes is toppling instability.In secondary toppling failures,these instabilities are stimulated through some external factors.A type of secondary toppling failure is"slide-toe-toppling failure".In this instability,the upper and toe parts of the slope have the potential of sliding and toppling failures,respectively.This failure has been investigated by an analytical method and experimental tests.In the present study,at first,the literature review of toppling failure is presented.Then a simple theoretical solution is suggested for evaluating this failure.The recommended method is compared with the approach of AMINI et al through a typical example and three physical models.The results indicate that the proposed method is in good agreement with the results of AMINI et al’s approach and experimental models.Therefore,this suggested methodology can be applied to examining the stability of slide-toe-toppling failure.

Genetically identified complete hydatidiform mole coexisting with a normal fetus following IVF-ET

A complete hydatidiform mole coexisting with a fetus following in vitro fertilization and embryo transfer (IVF-ET) is a rare event. The diagnosis is often not easy because of the morphological similarity to a partial mole, but important to the treatment. We present a recent case in which STR polymorphism analysis clearly revealed a different genetic origin for the fetal and molar parts. STR polymorphisms on 15 variable number tandem repeat loci and a gender-determination locus, which were detected by polymerase chain reaction, indicating that the cord/placenta and molar tissue were parental and androgenous, respectively. During follow-up, the patient developed persistent gestational trophoblastic tumor (GTT) which was successfully treated with chemotherapy. In this case, STR polymorphism analysis exactly diagnosed a twin pregnancy consisting of a complete hydatidiform mole and a fetus.