07MnNiMoDR与10Ni3MoVD组焊焊接试件性能研究

通过试验研究,获得了07MnNiMoDR与10Ni3MoVD(均为淬火+回火)两种高强合金钢建造的低温设备组焊焊接试件的室温拉伸试验、弯曲试验、冲击试验和硬度试验检测数据及金相组织图。试验数据表明,(1)焊接后焊缝的抗拉强度高于07MnNiMoDR母材。(2)焊缝区、热影响区、母材区的材料伸长率一致,焊接接头的塑性和完整性较好。(3)在-50℃条件下,焊缝区的冲击功大于80J,母材和热影响区的冲击功明显高于焊缝区。(4)母材区与相应热影响区的硬度值偏差不大,高于焊缝区。同一区域不同部位测试结果偏差较小,焊缝区、热影响区及母材区淬硬倾向不明显。金相试验组织图分析结果与试验数据吻合良好。

水工混凝土强度标准有关问题的探讨和改进建议

SDJ 207—1982《水工混凝土施工规范》和DL/T 5144—2001《水工混凝土施工规范》的强度标准主要来自ACI 214—1977《混凝土强度试验结果评定推荐方法》。三者的配制强度确定方法相同,存在的主要问题是:①设计强度仍按定值计;②强度保证率凭经验确定;③没有考虑抽样检验因素(试件组数和两类错误)。ACI 214—1977的验收强度随抽取试件组数的增多而提高,不合情理;SDJ 207—1982的验收强度等同于配制强度,偏高,可能会有50%合格的混凝土被错判为不合格;DL/T 5144—2001则误将ACI 214—1977的配制强度当做验收强度,都应该加以改进。笔者建议在按正态分布计的设计强度的基础上,强度标准差按已知计,考虑抽样检验因素——试件组数和两类错误,以总体均值衡量的一次计量抽样检验方案来确定验收强度和配制强度。

Research on thermocouple transient thermometry technology based on LabVIEW

Based on LabVlEW platform, a distributed dynamic storage testing system is designed for measuring transient high temperature signals of explosion field. Using a highpower semiconductor laser as heat source, a traceable dynamic calibration system is established to perform dynamic calibration of thermocouples. With quantumbehaved particle swam optimization （QP-SO） algorithm on MATLAB platform, a model of dynamic compensation filter is established. It is used by LabVIEW that calls MATLAB Script nodes or COM components to accomplish the mixed programming of LabVIEW and MATLAB, further to compensate the temperature values of the thermocouples dynamically. The experimental results show that the technique that combines temperature measurement system with LabVIEW platform is applied well in testing the explosion temperature of ther mobaric weaponry and makes the compensation values closer to the actual signals.

Generating test cases for software configuration testing

Software configuration testing is used to test a piece of software with all kinds of hardware to ensure that it can run properly on them. This paper generates test cases for configuration testing with several common methods, such as multiple single-factor experiments, uniform design, and orthogonal experiment design used in other fields. This paper analyzes their merits and improves the orthogonal experiment design method with pairwise testing, and decreases the testing risk caused by incomplete testing with a method of multiple-factors-covering. It presents a simple factor cover method which can cover all the factors and pairwise combinations to the greatest degree. Some comparisons of these methods are made on the aspects of test suite scale, coverage, and usability, etc..

An Effective Long String Searching Algorithm towards Component Security Testing

In the execution of method invocation sequences to test component security,abnormal or normal information is generated and recorded in a monitor log. By searching abnormal information from monitor log,the exceptions that the component has can be determined. To facilitate the searching process,string searching methods could be employed. However,current approaches are not effective enough to search long pattern string. In order to mine the specific information with less number of matches,we proposed an improved Sunday string searching algorithm in this paper. Unlike Sunday algorithm which does not make use of the already matched characters,the proposed approach presents two ideas — utilizing and recycling these characters. We take advantage of all matched characters in main string,if they are still in the matchable interval compared with pattern string,to increase the distance that pattern string moves backwards. Experimental analysis shows that,compared to Sunday algorithm,our method could greatly reduce the matching times,if the scale of character set constituting both main string and pattern string is small,or if the length of pattern string is long. Also,the proposed approach can improve the search effectiveness for abnormal information in component security testing.

Component system regression testing method based on CTAM

The emphasis of component system regression testing is retesting of the event interaction between updated components and other components in a system.A component system regression testing method based on a new component testing association model （CTAM） is proposed.First,the modification-affected component groups are identified by the impact analysis on CTAM,and each component in this group is assigned with an influence degree.Then,previous test cases are selected according to the influence degree,to generate the minimal regression test suite.Compared with traditional methods,CTAM is derived from the statistic on the interactive events that occurred in previous test executions,and focuses on the complicated relationship between components,which is more applicable to the component system regression testing.

AN ALGORITHM FOR FAULT DIAGNOSIS BASED ON COMBINATORIAL DESIGN APPROACH FOR TESTING

Much research has been done mainly in testcase generation and its effect for com-binatorial design approach for testing. This letter presents an algorithm for fault diagnosis basedon the approach. It can conclude that the factors, which cause errors, must be in a very smallrange through analyzing the test cases after testing, and retesting with some complementary testcases. The algorithm can provide a very efficient and valuable guidance for the debugging andtesting of software.

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

The Setting of Sipping Test Devices for Irradiated Fuel in Nuclear Power Plant

The sipping test devices are used to identify the defective fuel. The defective fuel can be identified by detecting the occurrence of the fission products that are entrained by the medium rising around the fuel rods. This project is the setting of the two kinds of the three sipping test devices to inspect the tightness of the irradiated fuel assembly from two units NPP （nuclear power plant）. The in-mast sipping shared by two units is used for qualitative tightness test of each fuel assembly during refueling operation above the reactor. The two poolside sipping is used for quantitatively confirming the diagnosis of the in-mast sipping and identifying the tightness of the fuel at the side of the fuel storage pools of each unit after refueling. The project was implemented by research, design manufacture and calibration of these three devices and completed successfully with serious quality assurance and quality control. The performance of these devices is well demonstrated.

Component-based software reliability analysis incorporating imperfect debugging and change-point

Against the deficiencies of component-based software(CBS) reliability modeling and analysis,for instance,importing too many assumptions,paying less attention to debugging process without considering imperfect debugging and change-point(CP) problems adequately,an approach of CBS reliability process analysis is proposed which incorporates the imperfect debugging and CP.First,perfect/imperfect debugging and CP are reviewed.Based on the queuing theory,a multi-queue multichannel and infinite server queuing model(MMISQM) is presented to sketch the integration test process of CBS.Meanwhile,considering the effects of imperfect debugging and CP,expressions for fault detection and correction are derived based on MMISQM.Numerical results demonstrate that the proposed model can sketch the integration test process of CBS with preferable performance which outperforms other models.

Undrained response of reconstituted clay to cyclic pure principal stress rotation

A series of monotonic and rotational shearing tests are carried out on reconstituted clay using a hollow cylinder apparatus under undrained condition. In the rotational shearing tests, the principal stress axes rotate cyclically with the magnitudes of the principal stresses keeping constant. The anisotropy of the reconstituted clay is analyzed from the monotonic shearing tests. Obvious pore pressure is induced by the principal stress rotation alone even with shear stress q0=5 k Pa. Strain components also accumulate with increasing the number of cycles and increases suddenly at the onset of failure. The deviatoric shear strain of 7.5% can be taken as the failure criterion for clay subjected to the pure cyclic principal stress rotation. The intermediate principal stress parameter b plays a significant role in the development of pore pressure and strain. Specimens are weakened by cyclic rotational shearing as the shear modulus decreases with increasing the number of cycles, and the shear modulus reduces more quickly with larger b. Clear deviation between the directions of the principal plastic strain increment and the principal stress is observed during pure principal stress rotation. Both the coaxial and non-coaxial plastic mechanisms should be taken into consideration to simulate the deformation behavior of clay under pure principal stress rotation. The mechanism of the soil response to the pure principal stress rotation is discussed based on the experimental observations.

Flexural Behavior of FRP-Reinforced Concrete Composite Member

Concrete Filled FRP （Reinforced Polymeric Plastic） Tubes （CFFT） and Reinforced Concrete Filled FRP Tubes （RCFFT） are known to have the capability to enhance structural performance in terms of structural stability, ductility, as well as chemical resistance when compared with conventional concrete members. In this study, the authors evaluate the structural performance of the CFFT and the RCFFT through flexural tests for the purpose of applying the members as flexural ones. Moreover, the compressive behavior of the CFFT and the RCFFT members was investigated to examine their confinement effects. Based on the experimental and analytical results of the compressive behavior of the members, equations for estimating the ultimate compressive strengths of the CFFT and the RCFFT were proposed. In addition, the degree of improvement on the flexural performance of the RCFFT member strengthened by the FRP was analyzed from the flexural tests.

混凝土验收强度和配制强度的确定方法

混凝土的验收强度和配制强度关系工程安全和造价,应结合混凝土强度的实际,用数理统计方法加以确定。但是现行的方法,有的没有将强度都按正态分布计;有的强度标准差按未知计;有的抽样检验因素(试件组数和两类错误)没有考虑或没有全部考虑;还有的甚至不采用数理统计方法而采用经验法;……,致使所得验收强度和配制强度不正确,也不统一。本文针对存在的问题,提出以按正态分布计的设计强度为基础;强度标准差按已知计;考虑试件组数和允许较小的抽样检验的第Ⅱ类错误(将不合格的漏判为合格)确定试件强度平均值的验收强度;在此基础上,再允许较小的抽样检验的第Ⅰ类错误(将合格的错判为不合格),确定配制强度和预期强度正态分布;再在预期强度正态分布的基础上,考虑试件强度最小值随试件组数增多而降低的统计规律,确定试件强度最小值的验收强度。最后举例说明本文方法的合理性。

美国ACI214-77标准的主要问题

本文评析美国ACI 214-77标准存在的主要问题———设计强度没有按正态分布计;强度允许低于设计强度的概率凭经验确定;确定配制强度没有考虑抽样检验因素(试件组数和两类错误);试件组数增多验收强度提高,不合情理;没有考虑用户风险;没有规定分批检验。根本原因是:没有完全将混凝土强度按正态分布计,也没有全面运用数理统计方法。

美国混凝土学会(ACI)混凝土强度标准的主要问题

本文评析美国混凝土学会(ACI)强度标准存在的主要问题:(1)只将预期强度按正态分布计,没有将设计强度也按正态分布计,而是按定值(或单值)计;(2)没有全面准确地按数理统计方法确定配制强度和验收强度。建议应作重大改进。