Papers by Keyword: Frequency

Abstract: nfluence of frequency on fretting fatigue damage behavior of Al-Zn-Mg alloy was studied in this paper. Fretting fatigue lives and damage characteristics of Al-Zn-Mg alloy were researched under different frequencies. Macroscopic tests and microscopic analysis were used to study on influence of frequency on fretting fatigue damage behavior of Al-Zn-Mg alloy. Fatigue lives would be greatly reduced by fretting under the experimental conditions in this paper. With frequency increasing, fretting fatigue lives were firstly decreased and then increased (f=9Hz). Fretting scar, which was the important reason for fretting fatigue crack initiation, was caused by embedding debris; eventually, crack initiated at the edge of the fretting scar. Fretting fatigue fracture is a whole process of crack initiation, propagation and final fracture. And final fracture increased with frequency reducing, which was generally occurred near the center of the fracture.

Abstract: This paper uses the theories of phonemics,phonology and mathematical statistics to concrete research the 2500 commonly-used standard Chinese characters phonological system in different levels, including the statistics and analysis of three aspects: words frequency, syllable frequency and phoneme frequency. Some resulted have gained that: 1) There is a obvious difference in the words frequency distribution of the 2500 commonly-used Chinese characters,2) The number of homophones has an inverse proportion with its total frequency,3)The combination ability of the unaspirated initials,monophthong vowels and falling tone, whose combining ability is stronger than others. This paper provides data and certain reference value for the further study on phonological system of standard Chinese.

Abstract: This paper from the perspective of phonology, phonetics and statistics,combining the three basic principles, to describe and research the phoneme system of 5190 Tibetan consonant of modern library within the closed space. According to the statistics and analysis of the initial and final distribution pattern, the structure types of initial and final, the relationship between Tibetan parts and the structure of initial and final in modern library of 5190 Tibetan consonant, the study found that, 1) the frequency distribution of the modern Tibetan initials is in equilibrium state, and the frequency distribution of finals is centralized,2) the combination ability of base-word initials is significantly higher than other initials which by the combination of basic word and other components,3) the combination ability of a and the combination of a with add-back letter is the strongest in all finals. This paper provides data and certain reference value for the further study on Tibetan phoneme of modern Tibetan.

Abstract: This paper introduced a concept of frequency inspection coefficient to find relationship among frequency inspection coefficients of static flexibility, strain and structure dynamic load. Explored this theory resemblance of structure stiffness evaluation which based on frequency inspection coefficient and static flexibility inspection coefficient separately, and verified reliability of this method which aiming at arch bridge via the result of measured static and dynamic test data of sample bridge.

Abstract: The rotational seismic inputs for building design were discussed. The free ground rotations and the relation between free ground rotations and basement rotations were derived. The results show that the relation depends on the basement size, site and seismic frequency. For most building, the differences between the free ground rotations and the basement rotations are small. The suggestion is that for tall buildings the free ground rotations can be taken as the seismic input, but for low-rise building with large basement, the response spectra in short period region should be reduced.

Abstract: Determination of a runway orientation is a critical task in the planning and design of an airport, and runway orientation is made according result of wind coverage. But there are many shortcomings in current method of wind coverage calculation, such as less precision, process miscellaneous and result simplex, when using the method in determination of a runway orientation. Aim at the situation, through analysis the relation between wind direction and runway orientation, the method is built that becoming all wind to cross wind for runway. Then according annual wind statistic data and requirement of max cross wind, frequency of cross wind exceed limited value for eight runway orientation are calculated in certain airport area. According the result, relation curve between frequencies of cross wind exceed limited value and runway orientation is made. Now, the best and all possible orientation for runway is get under requirement of max cross wind. At last, the method for determination of a runway orientation based on frequency of cross wind is put forward, and the method is a new thought for planning and design of an airport.

Abstract: In order to study the influence of the central buckle to the long-span suspension bridge structure mechanical characteristic, the Siduhe Bridge in Hubei Province was taken as the research background, the study were carried on the vibration characteristics, the driving comfort and the vehicle-bridge coupled vibration, which effected by the central buckle of the long-span suspension bridge. The results show that the central buckle has great impact on the large-span suspension bridge natural frequency, the central buckle can large extent increase the structure rigidity, improve the structure self-vibration frequency, and enhance the stability. The vehicle has good comfortable performance when droved on the bridge, and the central buckle has less effect on the comfortable quality. The central button setting can effectively reverse the lower stiffening girder displacement, and improve the stability of the bridge traffic.

Abstract: This paper focus on the model updating of civil structural systems. Traditional modal test method can identify the frequency of the civil structure accurate, but it is difficult to identify the mass-normalized mode shape. By adding a series of known masses to the structure, measuring the frequency of this mass-modified system, and only using this set of frequency data, the mass-normalized mode shape of the structure can be identified. And the model updating method was developed, which constructed an objective function through the frequency of the measurement and the FE model, corrected the FE model's parameters to minimize the objective function. The example was included to show the capabilities of the technique. The finite element model of the fixed-free beam was updated by the dynamic characteristics which was identified from the modal test, the results show that updated results coincided with the experience of the analyst.

Abstract: As the development of the economic society, the new orbit form such as modern tram track arises at the historic moment. Considering the urban internal environment, a higher request is put forward on vibration and noise reduction. This passage is devoted to analyze the noise reduction performance of the granule material, which gained by recycling the waste rubber. We can draw the following conclusions by comparing the noise value and frequency characteristic analysis in different conditions: the new particle material, the ratio of which is 3mm and 5mm, can suppress the noise in different frequency. Especially, the effect is obvious in high frequency area about 1000Hz to 1500Hz.When the track is under a vertical excitation, the combined structure can suppress the rail acoustic radiation noise obviously within 0 to 4000Hz frequency and 1/3 octave center frequency. The horizontal reduction of the noise will be reduced as the increasing of the distance between the vibration source and the test point.

Abstract: The dynamic property of carbon filled rubber materials is related to pre-load, excitation frequency and amplitude etc. A model by superimposing an elastic model, a viscoelastic model and an elastic-plastic model is presented to model the dynamic property of a rubber isolator. In this paper, this approach is adopted to calculate the dynamic property of a rubber isolator. It is shown that the presented model can predict the amplitude and frequency dependency of a rubber isolator with small relative errors. The validity of this model is verified by experiment. The approach described in this paper can be used in the design and calculation for rubber isolators.