1,055 research outputs found
Internal low-frequency noise analysis of high-speed train under mechanical excitation
With the speeding up of high-speed trains, the radiation noise generated from plates of the vehicle body was becoming increasingly obvious; however, fewer researches were performed on this aspect at present. The dynamic equation of the head vehicle of the high-speed train and the vehicle-track coupled dynamic model were both established, and then the dynamic load excitation of the vehicle body on uneven tracks was eventually obtained. With the material properties attributed, the finite element model of the vehicle body was eventually obtained to solve the modal, which was subsequently compared with the experimental one to verify the accuracy of the model. Based on the structural-acoustic coupling boundary element method, the noise distribution inside the passenger compartment of the high-speed train was calculated. Moreover, with the employment of the acoustic transfer vector (ATV) technology, the contribution coefficients of each plate of the vehicle body to the maximum sound pressure point were calculated. It was shown through the result that when the sound-absorbing materials inside the vehicle were ignored at the speed of 300 km/h, the sound pressure level inside the high-speed train ranged between 80 dB and 93 dB. Furthermore, when transverse ribs were added to the passenger compartment floor, its contribution coefficient to the sound pressure at the field points could be reduced, thus the noise inside the high-speed train could be improved
A Comparative Study of Survival, Metabolism, Immune Indicators, and Proteomics, in Five Batches of Japanese Scallop Mizuhopecten yessoensis under Short-Term High Temperature Stress
Five batches of the Japanese scallop Mizuhopecten pyessoensis were tested for survival rate, oxygen consumption, catalase (CAT) and superoxide dismutase (SOD) activities, total antioxidant capacities (T-AOC) contents, and proteomics under short-term high temperature conditions. The five batches, (W1, W2, W3, W4, W5) selected from the established 21 ‘ivory white’ M. yessoensis batches, had higher survival rates than the other batches after one year of culture. Initial rearing water temperature of 15°C was increased by 1°C per day with a cooling and heating system. The temperature was raised until over 50% of the scallops from 3 batches died. This occurred at 30°C. The higher than normal culture temperature conditions showed significant or highly significant differences in the responses of some of the batches. Some showed significantly higher survival rates and significantly different rates of oxygen consumption. CAT activity, SOD activity and T-AOC content was similar in the five batches, and all three indices were significantly lower in W3 and W5 than in the other batches (P<0.01). Expression patterns of MDA content were opposite to those of CAT activity, SOD activity and T-AOC content. Protein profiles of all five batches were similar; the sizes of the predominant bands ranged from 20-110 kDa. We identified twenty-eight proteins with high scores in the database. These included heat shock proteins (HSPs), glucose-regulated protein 94, and arginine kinase
Feasibility Study of Hybrid Inverse Planning with Transmission Beams and Single-energy Spread-out Bragg Peaks for Proton Flash Radiotherapy
Ultra-high dose rate (FLASH) proton planning with only transmission beams
(TBs) has limitations in normal tissue sparing. The single-energy spread-out
Bragg peaks (SESOBPs) of FLASH dose rate have been demonstrated feasible for
proton FLASH planning. A hybrid inverse optimization method was developed to
combine the TBs and SESOBPs (TB-SESOBP) for FLASH planning. The SESOBPs were
generated from spreading out the BPs by pre-designed general bar ridge filters
and placed at the central target by range shifters to obtain a uniform dose
within the target. The SESOBPs and TBs were fully sampled field-by-field
allowing automatic spot selection and weighting in the optimization process.
The TB-SESOBP plans were validated in comparison with the TB only (TB-only)
plans and the plans with the combination of TBs and BPs (TB-BP) regarding 3D
dose and dose rate distributions for five lung cases. Comparing to the TB-only
plans, the mean spinal cord D1.2cc drastically reduced 41%, the mean lung V7Gy
and V7.4Gy moderately reduced by up to 17% and the target dose homogeneity
slightly increased in the TB-SESOBP plans. Comparable dose homogeneity was
achieved in both TB-SESOBP and TB-BP plans. Besides, prominent improvements
were achieved in lung sparing for the cases of relatively large targets by the
TB-SESOBP plans comparing to the TB-BP plans. The targets were fully covered
with the FLASH dose rate in all the three plans. For the OARs, V40Gy/s = 100%
was achieved by the TB-only plans while V40Gy/s > 85% was obtained by the other
two plans. We have demonstrated that the hybrid TB-SESOBP planning was feasible
to achieve FLASH dose rate for proton therapy. The hybrid TB-SESOBP planning
has great potential in improving OAR sparing while maintaining high target dose
homogeneity, and can be potentially implemented for adaptive radiotherapy
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