Papers by Keyword: Assessment

Abstract: The assessment of timber structures is a permanent task to check the normal function of individual structural timber elements. Non-destructive testing methods are preferred but the value of the information is limited due to the performance of the applied assessment method. However, X-ray is a technology which allows a view into the structural member or the connections. The mobile X-ray technology has been used in laboratory tests and practical situations at existing structures and led to excellent results which allowed detailed analyses. The method and its possibilities for non-destructive testing of timber structures will be presented. The results reached show a high potential for an effective assessment of existing structures including connections and structural timber members.

Abstract: Withdrawal resistances of wood have been applied for in situ assessment of wood in existing timber structures. The author had proposed method to estimate shear strengths of wood from measured withdrawal resistances of probes which are screwed into wood. In order to verify the accuracy of these estimated shear strengths by proposed methods, withdrawal resistance measurements and shear loading tests were conducted for wood. Single withdrawal resistance measurement was applied for wood specimens, and estimated shear strengths from withdrawal measurements were compared to the measured shear strengths by shear loading tests of wood. Correlation between the estimated shear strengths and measured shear strengths of specimens was reasonably good (R2=0.73). Multiple coaxial withdrawal resistance measurement which can provide distribution of shear strengths in cross-section of wood was also proposed. The average of estimated shear strengths by single withdrawal resistances was 7 percent less than that of measured shear strengths. The average of estimated shear strength by multiple coaxial withdrawal resistances was 3 percent greater than that of measured shear strengths. The single withdrawal measurements and multiple coaxial withdrawal resistances are available to estimate shear strengths of wood and shear strength distribution in the cross-section of wood. Estimated shear strengths obtained from these methods will be valuable for strength based in situ assessment of wood.

Abstract: It is convenient and effective to use Monte Carlo simulation (MCS) technique in project schedule risk analysis and assessment, but at the same time, the indexes put forward by scholars up to now is quite few, leaving construction schedule risk assessment still difficult to carry out. Therefore, based on PERT network assumption, the shortcomings of current project schedule risk indexes are summarized and new project schedule risk index is put forward to estimate the criticality of each activity and path to provide more information for project schedule controllers. In the case studied, with the application of the new index, the critical index of each activity is given and divided into five levels, and the new index put forward in this paper shows great superiority over the classic indexes.

Abstract: In order to estimate the present exposure risk of Cadmium dietary intake by inhabitants in a W-Mo mining area, South China, a dietary investigation was conducted with stratified cluster random sampling method. According to the result, a total of 7 food groups, including rice, vegetable, meat, chicken and egg, were sampled from contaminated areas using the total dietary study method. Rice consumption took up 81.5% of food consumption. Cadmium content in 45.8% of 306 rice samples, 11.1% of 252 vegetable samples, and 4.8% of 21 chicken samples exceeded the limit. Risks of cadmium in study area are between 1.0E-06 and 1.0E-03, which is acceptable but need further attention to reduce them. Rice products were the highest contribution, which took up about 80.1%. The results showed that Cadmium intake was much higher around W-Mo ore deposit than that in reference area.

Abstract: In this paper, the indexes that are used to assess the influence of road construction on Inner Mongolia grassland have been proposed based on the environment protection perspective. The Analytic hierarchy process was employed to evaluate the importance of different indexes regarding to influence. These indexes would be used to provide information for decision making about road construction in order to achieve the sustainable development of grassland.

Abstract: Aimed to implement effective maintenance to ensure that the highway electromechanical system performs its intended functions, the output results of the fore-warning system are considered as the basis of maintenance policy. The fore-warning system is built based on the study of the fault features and causes of highway electromechanical system. As a failure warning information platform, the fore-warning system of highway electromechanical system analyzes fault factors and the relationship associated, in order to perform timely appropriate preventive maintenance measures at the right time. Taking advantage of Fault Tree Analysis, failure rates or failure probabilities of individual basic events existing in the complex system are estimated, which would be synthesized to determine whether the system failure rate reaches the threshold.

Abstract: In this paper, the concept of the degradation modeling and its development status is introduced first. Then the relationship between the degradation model and the distribution of failure time is given. Third the related research of the degradation modeling is elaborated from two situations of no stress factors and stress factors. Finally it analyzes the hot issues in the field of degradation modeling briefly, and looks forward to the next study.

Abstract: In order to analyze the reliability of high reliability and long-life products, the method which is based on the distribution of random coefficient is an effective technical approach. In this paper, first it is analyzed the steps of statistical analysis for degradation data based on the distribution of random coefficient. Then it is discussed in detail the degradation models of random coefficient distribution, the problems of distribution under these models and the advantages and disadvantages of each model.

Abstract: In order to solve the key technology and method in reliability study of the long-life products, the analysis method of degradation data based on the degradation amount distribution was proposed in this paper. On the basis of statistical model, by analyzing three models of degradation amount distribution, it can be got there is a large number of reliability information with high-reliable and long-life products in performance degradation data. In the case of not getting the failure data by life test and accelerated life test, reliability assessment and life prediction could be carried out for high reliability and long life products with performance degradation data.

Abstract: The object of the statistical analysis is the statistical information. To correctly identify the type of statistical information is the most important prerequisite for rational use of statistical analysis methods. In this paper, the common methods for normality test are introduced theoretically. And the figure test and partial kurtosis test of normal distribution are proposed with detailed testing steps, suitable situation and mathematical model. It is demonstrated by simulation that both have good test results and practical value.