• Steel and Composite Structures
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• 제47권1호
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• pp.91-102
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• 2023

To study the evaluation standard and control limit of mortar filling layer void length, in this paper, the train sub-model was developed by MATLAB and the track-bridge sub-model considering the mortar filling layer void was established by ANSYS. The two sub-models were assembled into a train-track-bridge coupling dynamic model through the wheel-rail contact relationship, and the validity was corroborated by the coupling dynamic model with the literature model. Considering the randomness of fastening stiffness, mortar elastic modulus, length of mortar filling layer void, and pier settlement, the test points were designed by the Box-Behnken method based on Design-Expert software. The coupled dynamic model was calculated, and the support vector regression (SVR) nonlinear mapping model of the wheel-rail system was established. The learning, prediction, and verification were carried out. Finally, the reliable probability of the amplification coefficient distribution of the response index of the train and structure in different ranges was obtained based on the SVR nonlinear mapping model and Latin hypercube sampling method. The limit of the length of the mortar filling layer void was, thus, obtained. The results show that the SVR nonlinear mapping model developed in this paper has a high fitting accuracy of 0.993, and the computational efficiency is significantly improved by 99.86%. It can be used to calculate the dynamic response of the wheel-rail system. The length of the mortar filling layer void significantly affects the wheel-rail vertical force, wheel weight load reduction ratio, rail vertical displacement, and track plate vertical displacement. The dynamic response of the track structure has a more significant effect on the limit value of the length of the mortar filling layer void than the dynamic response of the vehicle, and the rail vertical displacement is the most obvious. At 250 km/h - 350 km/h train running speed, the limit values of grade I, II, and III of the lengths of the mortar filling layer void are 3.932 m, 4.337 m, and 4.766 m, respectively. The results can provide some reference for the long-term service performance reliability of the ballastless track-bridge system of HRS.

• 생명과학회지
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• 제28권4호
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• pp.483-487
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• 2018

사이퍼메트린은 피레스로이드 계열 살충제로서 오랫동안 농업과 가정에서 이용되어 왔으며 그들의 잔여 성분과 독성에 대한 경각심이 고취되고 있다. 부산 인근의 해안에서 분리된 Cellulophaga lytica DAU203 균주가 사이퍼메트린의 생물학적 분해 활성을 나타내었다. DAU203 균주는 최소 배지에서 유일 탄소원으로 사이퍼메트린을 첨가하였을 때, 이를 분해하여 탄소원으로 활용 하였다. 반응표면분석법을 통하여 DAU203 균주의 사이퍼메트린 분해를 위한 최적 조건을 탐색하였다. 온도, pH와 yeast extract 첨가 농도와 같은 인자가 분해 활성에 영향을 미치는 것으로 분석 되었고, 각각의 최적 값은 $33.4^{\circ}C$, pH 7.7와 2.4%(w/v)이다. 최적 조건에서 DAU203 균주는 5일 동안 대략 83.7%의 사이퍼메트린을 분해하였다. 본 연구는 미생물 중에서 잘 연구되지 않은 해양 미생물에 대한 활용 가능성을 증가시켰다고 판단된다.