加筋土挡墙的灾后结构性能评价方法的研究

为了建立加筋土挡墙性能评价方法,从而有针对性的采取应对措施,在参考了大量现有的工程检测方法的基础上,结合加筋土挡墙结构的破坏特征,提出了一套合理而科学的检测方法,使得各个检测项目的检测数据能科学而全面的反映出加筋土挡墙的综合质量。进行灾后现场检测时,当出现病害要素,先进行单项要素评定,然后再把每个评定要素按照整个评定体系进行评估,最终对挡土墙进行综合质量分类:安全,注意,危险三个安全等级。最后通过工程实例应用证明了该方法的适用性。

简论体育课程的建构性

本文主要从体育课程的建构性内涵、知识性建构、过程性建构、人本性建构、人文性建构和后现代性建构6个部分对体育课程的建构性进行解读,以实现体育课程的和谐流转。

Is There Hysteresis in Unemployment in OECD Countries？ Evidence From Panel Unit Root Test With Structural Breaks

This study tests the hysteresis hypothesis of unemployment in fifteen OECD countries by using panel unit root tests which allow for structural breaks. We apply annual unemployment rates covering 1985-2008 periods. We test whether unemployment rates are stationary by using second generation tests which allow cross section dependency among series and panel unit root test based on structural break advanced by Carrion-i-Silvestre, Barrio-Castro and Lopez-Bazo （2005）. We find series as a stationary process with structural breaks according to Carrion-i Silvestre et al. （2005） test, while we find series as unit root process with second generation panel unit root test. According to the Carrion-i Silvestre et al. （2005） test, we find the evidence of absence of hysteresis in analyzed countries. As a result, temporary shocks have temporary effects on unemployment instead of permanent effect. Structural factors can affect the natural rate of unemployment and, therefore, unemployment would be stationary around a process that is subject to structural breaks. So, there still exists a unique natural rate of unemployment to which the economy eventually will converge.

Experimental Research on Erbium-doped Superfluorescent Fiber Source

The effects of the variations in fiber length,fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs).The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated.By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port,the pump power dependent on MWS becomes independent of pumped EDF length.This is a novel phenomenon that hasn’t been reported up to now,and should be helpful to SFS fabrication and theory analysis.By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ～20 channels (from 1 542 nm to 1 559 nm) is got.The MWFS has a channel spacing of ～0.8 nm which satisfies ITU-standard.The intensity fluctuation among channels is less than 0.5 dB,and the extinction ratio of all channels is above 14 dB.This kind of MWFS should be useful to wavelength division multiplexing systems.

The Structure and Stabilization Decom position of Linear Interconnected ControlSystem swith Multidelays

This paper gives a structural concept for linear interconnected control systems with multidelays,which is based on equivalence method of lyapunovs frequency area, a sufficient \{criteria\} is obtained for the interconnected stabilization of linear constant control system with multidelays,at the same time,the estimation of bound both time delays and parametric perturbation are given.

A case of malignant fibrous histiocytoma of the head after trauma and radiation therapy

Malignant fibrous histiocytoma(MFH) firstly described as"malignant fibrous xanthoma"by O' Brien and Stout in 1964, is the most common soft tissue sarcoma of late adult life.Uncertain histogenesis and numerous subtypes make MFH a rather controversial entity.MFH only rare arises from structures of the head and neck.When it does, it most often originates in facial structures, particularly the maxilla.This report details a case of a patient with malignant fibrous histiocytoma presenting clinically as a right-sided large indurated frontoparietal mass, three months after head trauma and eight years after radiation therapy for brain lymphoma located in the right frontal and parietal lobes.Radical excision was a surgical challenge because of the extensiveness of the lesion.

Data-based model free hysteresis identification for a nonlinear structure

In the last two decades, the damage detection for civil engineering structures has been widely treated as a modal analysis problem and most of the currently available vibration-based system identification approaches are based on modal parameters, namely the natural frequencies, mode shapes and damping ratios, and/or their derivations, which are suitable for linear systems. Nonlinearity is generic in engineering structures. For example, the initiation and development of cracks in civil engineering structures as typical structural damages are nonlinear process. One of the major challenges in damage detection, early warning and damage prognosis is to obtain reasonably accurate identification of nonlinear performance such as hysteresis which is the direct indicator of damage initiation and development under dynamic excitations. In this study, a general data-based identification approach for hysteretic performance in form of nonlinear restoring force using structural dynamic responses and complete and incomplete excitation measurement time series was proposed and validated with a 4-story frame structure equipped with smart devices of magneto-theological （MR） damper to simulate nonlinear performance. Firstly, as an optimization method, the least-squares technique was employed to identify the system matrices of an equivalent linear system of the nonlinear structure model basing on the exci- tation force and the corresponding vibration measurements with impact test when complete and incomplete excitations; and secondly, the nonlinear restoring force of the structure was identified and compared with the test measurements fi- nally. Results show that the proposed data-based approach is capable of identifying the nonlinear behavior of engineering structures and can be employed to evaluate the damage initiation and development of different structure under dynamic loads.

Features and genesis of micro-nanometer-sized grains on shear slip surface of the 2008 Wenchuan earthquake

In coseismic surface rupture zones caused by the 2008 Mw 7.9 Wenchuan earthquake, some thin-layered fault gouges with strong deformation were observed in different locations. In this paper, fault gouge samples were taken as research objects from the Bajiaomiao village in the south-west segment of the principal rupture and the Heshangping village and the Shaba village in the north-east segment of the principal rupture where larger displacements were measured. Fabric characteristics of the fault gouge samples and the morphologies and structures of micro-nanometer grains on Y-shear surfaces were then analyzed by using a stereoscope and SEM. Observation results showed that obvious Y- and R-shears and obvious scratches were well developed in coseismic gouges caused by the 2008 Wenchuan earthquake. Micro-nanometer grains in the fault gouge of the Wenhcuan earthquake were formed mainly due to breaking, grinding, and powdering of fault slipping friction surface. Heat caused by fault slipping(maybe also including heat caused by thermal decomposition) played an important role in producing micro-nanometer sized grains. Existence occurrence state of micro-nanometer sized grains on fault slip surface includes singled grains and their complexes with shapes of ball, silkworm, pancake and mass. The structures mainly include dispersed and close-packed structures besides a few of striped and layered structures. All these structures were formed at the extreme unbalance conditions caused by rapid deforming during an earthquake. There always exist some voids between structures due to loosely contact. Only alienated grains are included in the stripped structure. But there are some singled grains with no deformation in dispersed and close-packed structures besides complexes of grains with morphologies of ball, silkworm, pancake and mass. The striped and close-packed structures are the results of plastic deformation, and the dispersed and layered structures are the results of brittle deformation whereas loose contact of different structures was caused mainly by discontinuous dynamic friction(fault stick-slipping). The structures of the micro-nanometer sized grains in coseismic fault gouge caused by the Wenchuan earthquake are the geological records of seismic fault slipping(it is not pseudotachylite), which could be used as an index of paleo-seismic events.