基于替代试件模型的振动台迭代控制仿真分析

试件-台面相互作用会显著影响振动台加速度时程复现精度,迭代控制常常成为提高试验数据可靠性的重要手段。然而,砌体、钢筋混凝土等结构易于因开裂而进入非线性力学状态,往往不适合迭代加载。文中开展了基于替代试件模型的振动台迭代控制方法仿真研究,先构建一个与试件动力特性相近的替代试件模型,利用替代试件模型完成振动台迭代加载获得驱动命令后,再开展真实试件的振动台试验。仿真结果表明:基于替代试件模型的振动台迭代控制有效降低了试件-振动台相互作用对系统控制性能的影响,实现了台面加速度时程的高精度复现。

“轨道板-CA砂浆-支承层”复合模型(TCC)试件累积损伤特性研究

以CRTSⅡ型板式无砟轨道结为基础,浇筑“轨道板-CA砂浆-支承层”(TCC)复合模型试件(100 mm×100 mm×400 mm),通过MTS万能伺服液压疲劳试验机施加弯曲疲劳荷载,采用4点弯曲试验的方法,当应力水平S为75%、85%、95%时,探讨复合模型试件的弯曲疲劳变形特性和累积损伤演化过程。研究结果表明:与普通混凝土相比复合模型试件破坏时只出现了一条主裂纹将试件完整的分开,在层与层之间的黏结处出现了水平裂纹,且试件破坏呈现显著的延性破坏特征,TCC弯曲疲劳寿命可通过S-N曲线的单对数线性关系式表达;依据材料力学的理论,分析了将试验测定的位移-荷载数据转化为应力-应变曲线方法,并推导弯曲疲劳的动弹性模量计算公式;以疲劳应变的三阶段分析基础,结合弯曲疲劳试验数据、动弹性模量计算公式、疲劳寿命的线性回归方程等,提出了基于试验结果的“轨道板-CA砂浆-支承层”复合模型试件疲劳累积损伤演化方程。

大型石材幕墙抗震试验研究

对背栓连接的石材幕墙抗震性能进行了试验研究。通过对振动台上足尺模型试件进行模拟地震作用 ,检验其抗震性能 。

一种结构实验的计算机模拟技术

结合拉伸实验模拟实例,对在VC++6.0中用3DS MAX制作动画实现建筑结构实验模拟作了简要、清晰的介绍,指出综合运用3DS MAX与VC++6.0的优点,是实现实验模的一个新思路.

Testing agile requirements models

This paper discusses a model-based approach to validate software requirements in agile development processes by simulation and in particular automated testing. The use of models as central development artifact needs to be added to the portfolio of software engineering techniques, to further increase efficiency and flexibility of the development beginning already early in the requirements definition phase. Testing requirements are some of the most important techniques to give feedback and to increase the quality of the result. Therefore testing of artifacts should be introduced as early as possible, even in the requirements definition phase.

A software reliability growth model for component-based software incorporating debugging delay and imperfect debugging

In view of the problems and the weaknesses of component-based software （ CBS ） reliability modeling and analysis, and a lack of consideration for real debugging circumstance of integration tes- ting, a CBS reliability process analysis model is proposed incorporating debugging time delay, im- perfect debugging and limited debugging resources. CBS integration testing is formulated as a multi- queue muhichannel and finite server queuing model （MMFSQM） to illustrate fault detection process （FDP） and fault correction process （FCP）. A unified FCP is sketched, given debugging delay, the diversities of faults processing and the limitations of debugging resources. Furthermore, the impacts of imperfect debugging on fault detection and correction are explicitly elaborated, and the expres- sions of the cumulative number of fault detected and corrected are illustrated. Finally, the results of numerical experiments verify the effectiveness and rationality of the proposed model. By comparison, the proposed model is superior to the other models. The proposed model is closer to real CBS testing process and facilitates software engineer＇ s quantitatively analyzing, measuring and predicting CBS reliability. K

Energy Dissipation Within the Wave Run-Up at Stepped Revetments

To understand the processes and energy dissipation performance caused by turbulence during the wave run-up over a stepped revetment,hydraulic model tests with steady flow conditions are conducted and correlated with unsteady flow conditions of the wave run-up within a short time frame.Under irregular waves,the run-up reduction over a stepped revetment is dependent on the Iribarren number and decreases for decreasing Iribarren numbers.Velocity gradients are found to be similar in a steady and unsteady flow regime near the pseudo-bottom.

A fault injection model-oriented testing strategy for component security

A fault injection model-oriented testing strategy was proposed for detecting component vulnerabilities.A fault injection model was defined,and the faults were injected into the tested component based on the fault injection model to trigger security exceptions.The testing process could be recorded by the monitoring mechanism of the strategy,and the monitoring information was written into the security log.The component vulnerabilities could be detected by the detecting algorithm through analyzing the security log.Lastly,some experiments were done in an integration testing platform to verify the applicability of the strategy.The experimental results show that the strategy is effective and operable.The detecting rate is more than 90%for vulnerability components.

Developing the Model and Environment for Validation of a Class-8 Truck

Many studies have been conducted by analyzing crash data that included road profile, site conditions, vehicle configurations and weights, driver behavior, etc.. However, limited studies have been conducted evaluating the impact of these factors on crashes and/or rollover through simulations. This is mainly due to lack of availability of verified full vehicle flexible-body models. The verification process is costly as it requires instrumentation of a heavy vehicle, scanning of road surfaces, and collection of data by running the vehicle over different road conditions, performing various maneuvering, etc. This paper presents the reverse engineering process of a class-8 truck and validation of a full flexible-body simulation model of a Wabash 53-foot trailer against the strain data recoded from proving ground testing of an instrumented truck. Simulation results show that, with the exception of the noise from the strain gage data from instrumented test run at 30 mph, there is a good agreement in periodicity and relative amplitude with the ADAMS model. A comparison of strain data from the flex-body model and the instrumented truck shows that the modeling and verification approach presented in this paper can be confidently used to validate the full flexible-body models developed for specific analyses.

Stress-strain analysis of loess triaxial shear test by PFC^(3D)

In order to compensate for limitations of microscopic study on loess triaxial tests, taking the loess in Longxi area as an example, the authors established the loess triaxial test model by using PFC3D software and simulating tfiaxial shear test under the different confining pressures in 0 kPa, 50 kPa and 300 kPa. Compared with laboratory triaxial shear test, the numerical simulation test has a guiding role in loess mechanical strength analysis.

Modeling the Tensile Properties of Soybean Protein Yarns

The tensile properties of a series of soybean protein yarns are tested in USTER THINKPAID Ⅲ. A nonlinear viscoelastic model has been proposed to describe the tensile behavior of soybean protein yarns. The model is composed of a Maxwell element, a linear spring and a nonlinear spring. The tensile properties of soybean protein yam are analyzed. The stress-strain curves of the yams are fitted. The average breaking tenacity and specific work of rupture are calculated using the average breaking strain. Comparisons indicate that theoretical predictions conform the experimental results very well.

Testable model specification via statechart schema

XML is an important technology for Internet-based data exchange with far reaching capabilities be-yond for just data exchange. The paper describes the first results of a project that aims to explore the applicabil-ity of XML technology for web-based software engineering with the emphasis on collaborative software testing in-volving the use of statechart. The paper presents the approach of building the statechart schema with XML Sche-ma. It also describes the use of the schema in a web-based collaborative software testing CASE environment.

Clinical application of full automatic animal experimental cabin of normobaric/hypobaric hypoxia and high carbon dioxide

To explore the feasibility of the full automatic animal experimental cabin to establish the animal models in normobaric/hypobaric hypoxic and high carbon dioxide environment. Methods： Sixty SPF-class male DS rats were divided into 2 groups, 20 for normobaric, hypoxic conditions and the other 40 for hypobaric, hypoxic conditions. For each group, the pulmonary arterial pressure and carotid arterial pressure indicators of rats were examined by using the physiological multi-detector, and the pulmonary vascular changes in the structure were observed. Results： The normobaric/hypobaric hypoxic with high carbon dioxide environment can promote the formation of pulmonary hypertension and accelerate changes in pulmonary vascular remodeling, and promote the right ventricular hypertrophy. Conclusion： Clinical applications showed that the animal experimental cabin has observed and controlled accurately. The result was safe, reliable and reproducible. The cabin can successfully establish the pulmonary hypertension model in normobaric/hypobaric hypoxic with high carbon dioxide environment, and in order to study the physiological mechanism of a variety of circulation and respiratory diseases caused by lack of oxygen, which provided an experimental technology platform for clinical research.

An Application of Damage Detection Methods to A Real World Structure Subjected to Ground Motion Excitation

This paper aims at investigating the efficacy of different state-of-art damage detection methods when applied to real worm structures subjected to ground motion excitations, for which the literature contributions are, at present, still not fully comprehensive. To this purpose the paper analyses two test structures： （1） a four-story scaled steel frame tested on a shake table in a controlled laboratory conditions, and （2） a seven-story reinforced concrete building monitored during the seismic excitations of the 1999 Chi-Chi （Taiwan） Earthquake main shock and numerous fore and afiershocks. Some model based damage approaches and statistics based damage indexes are reviewed. The different methodologies and indexes are, then, applied to the two test structures with the final aim of analysing their performance and validity within the case of a laboratory scaled model and a real world structure subjected to input ground motion.

Fiducial generalized p-values for testing zero-variance components in linear mixed-effects models

Linear mixed-effects models are widely used in analysis of longitudinal data. However, testing for zero-variance components of random effects has not been well-resolved in statistical literature, although some likelihood-based procedures have been proposed and studied. In this article, we propose a generalized p-value based method in coupling with fiducial inference to tackle this problem. The proposed method is also applied to test linearity of the nonparametric functions in additive models. We provide theoretical justifications and develop an implementation algorithm for the proposed method. We evaluate its finite-sample performance and compare it with that of the restricted likelihood ratio test via simulation experiments. We illustrate the proposed approach using an application from a nutritional study.

A test of an early-type contact binary model by comparing the relations obtained from theory with those from observations

Contact binary systems,including massive,middle-mass and low-mass systems,have been observed.It is necessary to construct the evolutionary model for contact binary systems with all different masses.The model introduced by Huang,Song and Bi indicates some special and unique understandings of the physical processes occurring in the contact binaries.It is necessary to test whether this model can be applied to the early-type contact binaries.The best way to test a theoretical model is to know whether this model can explain the observational phenomena of such binaries.For this aim,a comparison is performed for the relations of mass-luminosity,mass-radius,and the distribution in the HR diagram obtained from the model introduced by Huang et al.and those from the astronomical observations.A good result is obtained by the comparison.This means the model can be used in calculating the evolution of early-type contact binaries,and can explain the observational phenomena of such binaries.

Testing for the parametric parts in a single-index varying-coefficient model

Single-index varying-coefficient models (SIVCMs) are very useful in multivariate nonparametric regression.However,there has less attention focused on inferences of the SIVCMs.Using the local linear method,we propose estimates of the unknowns in the SIVCMs.In this article,our main purpose is to examine whether the generalized likelihood ratio (GLR) tests are applicable to the testing problem for the index parameter in the SIVCMs.Under the null hypothesis our proposed GLR statistic follows the chi-squared distribution asymptotically with scale constant and degree of freedom independent of the nuisance parameters or functions,which is called as Wilks' phenomenon (see Fan et al.,2001).A simulation study is conducted to illustrate the proposed methodology.