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The existing researches have concluded that the number of gravity heat pipes, insertion depth and angle, filling rate, working fluid will affect the distribution of the internal temperature field of coal pile. However, there are few researches on the optimal arrangement of gravity heat pipes in coal pile. In order to solve the above problems, based on the gravity heat pipe heat transfer theoretical model, the heat source is equivalent to a sphere, and the effect of gravity heat pipe arrangement on the high temperature point of coal pile is analyzed by a combination of numerical simulation and experiment, and the optimal arrangement of gravity heat pipe is derived. The numerical simulation results based on Comsol software show that the depth of gravity heat pipe insertion has greater effect on the temperature of the high-temperature heat source point inside coal pile than the inclination angle of gravity heat pipe insertion. Under the same angle, the greater the gravity heat pipe arrangement depth is, the better. This means that the closer to the heat source, the better. Under the same depth, when the gravity heat pipe arrangement angle is 60, 90, 45 and 30°, the cooling range decreases in order. When the insertion depth of gravity heat pipe is 60 cm and the insertion angle is 60°, the highest cooling range reaches 61.2 ℃, and the coal pile has the best cooling effect. The experimental results based on the coal storage pile heat transfer test bench show that the optimal arrangement of gravity heat pipes is consistent with the simulation results, and the overall trend of the cooling rate is similar to the simulation results. With the increase of the inclination angle, the cooling rate of heat pipe decreases first and then increases, and the cooling rate reaches the maximum when the inclination angle of heat pipe insertion reaches 60°.

In order to investigate the changes of volatile flavor substances in the process of beeves spoilage, beeves with different storage time were employed. The volatile flavor substances of beeves in spoilage process were analyzed by using gas chromatography ion transfer spectroscopy (GC-IMS) and electronic nose. The results showed that a total of 55 volatile flavor substances were detected through GC-IMS, mainly including 12 ketones, 10 alcohols, 9 esters, 8 aldehydes and 4 hydrocarbons. GC-IMS and electronic nose analysis indicated that the types and contents of volatile flavor substances significantly increased during the spoilage process. The alcohols, aldehydes, esters, acids, furans, pyrroles, thiophenes, amines, pyridines and ethers continuously increased during the spoilage process. However, ketones, hydrocarbons, and sulfur compounds gradually increased and reached peak at the seventh day, and then gradually decreased. PCA and PLS-DA analysis suggested that there were significant differences in volatile flavor substances of beeves in spoilage process. Sixteen different volatile flavor substances were identified by variable importance for the projection (VIP) value, with the extension of storage, the contents of irritating and unpleasant flavor substances such as n-hexanal-D, n-hexanal-M, butyraldehyde-M, butyraldehyde-D, tetrahydropyrrole-M, isoamyl-D, isoamyl-M, n-propanol-D, 2,3-butanedione gradually increased, which could be used as potential biomarkers to distinguish beeves with different degrees of spoilage. This work provides a theoretical basis for monitoring beef spoilage process. [ABSTRACT FROM AUTHOR]

This paper reviewed the research and application works of laser in-situ curing of thermoplastic composite materials at home and abroad. Summarized three aspects of laser in-situ curing mechanism research, experiments, and temperature field simulation. Discussed the latest development trend of laser in-situ curing technology at last [ABSTRACT FROM AUTHOR]

In this paper, divisible difference set pairs are studied. By using difference set, difference set pairs and cyclotomic class, several classes of divisible difference set pairs are constructed. It not only expands the existence space of almost perfect binary sequences pairs, but also provides broader choice range of the address codes. [ABSTRACT FROM AUTHOR]

To investigate the γ pass rate limit of plan verification equipment for volumetric modulated arc therapy (VMAT) plan verification and its sensitivity on the opening and closing errors of multi-leaf collimator (MLC), 50 cases of nasopharyngeal carcinoma VMAT plan with clockwise and counterclockwise full arcs were randomly selected. Eight kinds of MLC opening and closing errors were introduced in 10 cases of them, and 80 plans with errors were generated. Firstly, the plan verification was conducted in the form of field-by-field measurement and true composite measurement. The γ analysis with the criteria of 3% dose difference, distance to agreement of 2 mm, 10% dose threshold, and absolute dose global normalized conditions were performed for these fields. Then gradient analysis was used to investigate the sensitivity of field-by-field measurement and true composite measurement on MLC opening and closing errors, and the receiver operating characteristic curve (ROC) was used to investigate the optimal threshold of γ pass rate for identifying errors. Tolerance limits and action limits for γ pass rates were calculated using statistical process control (SPC) method for another 40 cases. The error identification ability using the tolerance limit calculated by SPC method and the universal tolerance limit (95%) were compared with using the optimal threshold of ROC. The results show that for the true composite measurement, the clockwise arc and the counterclockwise arc, the descent gradients of the γ passing rate with per millimeter MLC opening error are 10.61%, 7.62% and 6.66%, respectively, and the descent gradients with per millimeter MLC closing error are 9.75%, 7.36% and 6.37%, respectively. The optimal thresholds obtained by the ROC method are 99.35%, 97.95% and 98.25%, respectively, and the tolerance limits obtained by the SPC method are 98.98%, 97.74% and 98.62%, respectively. The tolerance limit calculated by SPC method is close to the optimal threshold of ROC, both of which could identify all errors of ±2 mm, while the universal tolerance limit can only partially identify them, indicating that the universal tolerance limit is not sensitive on some large errors. Therefore, considering the factors such as ease of use and accuracy, it is suggested to use the true composite measurement in clinical practice, and to formulate tolerance limits and action limits suitable for the actual process of the institution based on the SPC method. In conclusion, it is expected that the results of this study can provide some references for institutions to optimize the radiotherapy plan verification process, set appropriate pass rate limit, and promote the standardization of plan verification.

Objective: To explore the feasibility of using the bidirectional local distance based medical similarity index (MSI) to evaluate automatic segmentation on medical images., Methods: Taking the intermediate risk clinical target volume for nasopharyngeal carcinoma manually segmented by an experience radiation oncologist as region of interest, using Atlas-based and deep-learning-based methods to obtain automatic segmentation respectively, and calculated multiple MSI and Dice similarity coefficient (DSC) between manual segmentation and automatic segmentation. Then the difference between MSI and DSC was comparatively analyzed., Results: DSC values for Atlas-based and deep-learning-based automatic segmentation were 0.73 and 0.84 respectively. MSI values for them varied between 0.29~0.78 and 0.44~0.91 under different inside-outside-level., Conclusions: It is feasible to use MSI to evaluate the results of automatic segmentation. By setting the penalty coefficient, it can reflect phenomena such as under-delineation and over-delineation, and improve the sensitivity of medical image contour similarity evaluation.

Objective: To separate and identify chemical constituents from Coptis chinensis., Method: The compounds were separated and purified by various chromatographic techniques. Their structures were identified on the basis of their physicochemical properties using spectral techniques such as NMR and MS., Result: Thirteen compounds were separated from ethanol extracts of C. chinensis, including seven lignans, three simple phenylpropanoids, two flavones and one phenolic acid, and identified as erythro-guaiacylglycerol-8-O-4'-(coniferyl alcohol) ether (1), threo-guaiacylglycerol-8-O-4'-(coniferyl alcohol) ether (2), (+)-pinoresinol (3), (+)-medioresinol (4), (+)-lariciresinol (5), (+)-5'-methoxylariciresinol (6), (+)-isolariciresinol (7), chlorogenic acid (8), ferulic acid (9), Z-octadecyl caffeate (10), rhamnetin (11), wogonin (12), and vanillic acid (13)., Conclusion: Compounds 1, 2, 4, 6, 10-13 were separated from the genus Coptis for the first time.